111. In some schools there are many computer classrooms. For example, students can do their mathematic exercises with a computer. The computer writes questions on the screens in front of the students, and the students answer on their keyboards. The computer knows Mary. This is their first lesson. The computer can give Mary the right lesson for her, neither too fast, nor too slow. And the computer can do this with many other students at the same time.
112. Students can also learn a foreign language with a computer. The computer gives lessons in pronunciation, grammar and the correct usage of words and phrases. Computers are very helpful and most students like their new computer teachers.
121. what is the sky? How high is it? Where is it? What lies above the sky? I am sure that you may have asked questions like these. They are very difficult to answer, aren’t they? What is the sky? Perhaps we can answer some of these questions now. Sky is vast space. It is all around the world. In the sky there is the sun, the moon, and all the stars.
122. Scientists have always wanted to know more about space. They use telescopes to obtain information. But this is not enough. So they want to send space ship to some of the other worlds in space. The moon is the nearest heavenly body to the earth. An airplane cannot fly to the moon, because the air only reaches a height of 240 kilometres. Then there is no air. But a rocket can fly even when there is no air.
123. A rocket is made of metal. There is a hot gas inside it. When it rushes out of the end of the rocket, the rocket is pushed up into the air. Rockets can fly far out into space. Rockets have already taken men to the moon. One day they may be able to go anywhere in space.
131. You’ll see a new doctor at a hospital near Shanghai if you go there. He’s very clever － but he never speaks and he didn’t go to medical college. He can work 24 hours a day and never tire. He’s only one metre tall and has a face like a TV screen. He has no arms or legs but lots of buttons and switches. He is Dr Robot.
132. Doctors often need to ask their patients about their health in the past. But busy doctors can only spend a few minutes with each patient. The robot doctor, however, can ask a patient questions for an hour if necessary. So when the human doctor meets his patient, he already has a lot of helpful information.
133. Dr Robot is really quite human. If you answer No to the question “ Is your father alive?”, Dr Robot will reply “I’m sorry to hear that” . There are plans for better robot doctors. But they will never take the place of human doctors. They can only help doctors to give their patients better service.
133. 机器人医生，颇有人的感情。如果机器人医生问你“你的父亲还活着吗？”而你回答“不”时，机器人医生就回答道“听了你的回答我感到难过”。 已经制定了设计更先进的机器人医生的计划。但是机器人医生永远代替不了医生。机器人医生只能帮助医生提高对病人的服务质量。
141. Thomas Edison wore many caps during his life. First he was just a poor working boy. He wore work caps of many kinds. Later in life he became a famous and great inventor. Then he wore the caps of many famous universities and colleges. But his most important cap was his thinking cap.
142. When he was a young boy, Edison’s thinking cap saved his mother’s life. One night, she suddenly fell ill. A doctor was called in. He had to operate on her at once, but there was not enough light in the room. Edison quickly put on his thinking cap. He got all the oil lights in the house and put them on a long table. Then he set up a big mirror behind them. At once the room became quite light. The doctor could operate, and his mother was saved.
143. Edison was thinking man. Yet, he was a working man and a doing man, too. He was good with his hands and his head. Edison’s famous inventions have changed the world greatly. Today many great trains run on electricity. Electricity light the streets of towns and villages. Science uses it every day.
144. Shining lights, records, moving pictures and ringing telephones are very common now. Edison’s thinking cap made them. Usually, caps keep the head warm. But thinking caps keep the world warm.
151. Here are some ideas for the future of transport in our cities, for example, the idea of the “carveyor”. This is a system of conveyor belts in the streets. There are three belts side by side. The first is very slow, the second travels at about ten miles per hour (m.p.h.) and the third goes at fifteen m.p.h. and has small cars on it.
152. To get on the carveyor, you just get on the slower belt, walk along it and change to the second belt. Then you walk along that one and get on the “fast” belt and sit in one of the cars. These belts never stop. In cities with carveyors we are not going to want cars or buses.
153. Then there is another idea: there are electronic tracks in the streets all round the city. Electric cars run on these tracks. All the tracks and all the cars are controlled by a central computer. If, for example, an engineer wants to go from a railway station to a large hotel, he goes out of the station and gets into one of these cars outside. He presses the button for his hotel. A signal is sent from the car to the central computer and the computer finds the route. Then the car takes its traveler to the hotel at about forty miles per hour. Easy, isn’t it? These are two wonderful ideas for the future. We must do something; we want to live in quiet and clean cities.
161. Have you ever been to the sea? It has always been a world of adventure for brave people. In the early days of sailing, many sailors left home to cross wide oceans. Often these early explorers were looking for new people to trade with. Today, explorers are still pushing their way through tons of ice in the far North. They are exploring some of the world’s last unknown waters.
162. Human beings have always loved the plants and animals that live in the sea. To look at sea life up close, people have had to design and produce all kinds of special equipment. Nowadays face masks, air tanks and diving suits are widely used in underwater exploration. With them, men can dive into deep water and be at home with the fish.
163. Once all deep－sea divers were men. But now, lots of women have become divers, too. In 1970, five girls stayed for two weeks in an undersea lab.
164. People cannot live under the water without special equipment. Yet people everywhere want to get to know the sea. They want to be in it and to be on it. They want to cross it. They want to use it. They want to explore it.
171. Many large cities are anything but beautiful. Streets are littered with trash. In this trash, however, there is still something that can be useful. If people want to solve the problem of waste, there is no time to be lost. They must work out ways of making use of good things which are just thrown away as waste.
172. When a car gets too old, it may not run any more. But the metal that the car was made of is still good. It can be put to use again. When a bottle is empty, it goes out in the trash. But bottle glass can be ground into sand and used to pave streets. First you have to fish out all the glass and metal. Then garbage from food can be changed into fertilizer.
173. Garbage can also be a good source for making building blocks, which are then covered with concrete. Now, more and more machines are designed for this purpose. Some day, people will watch films in a magnificent cinema which has been built out of garbage. Future buildings, roads, and cities may be made from garbage. But so far, building beautiful cities out of garbage is only a dream.
181. Can you imagine traveling to work in a one－man submarine? Some scientists believe that some day one－man submarines will be as numerous as automobiles are today. A famous French diver says, “One day soon, men will walk on the ocean floor as they do on the street.” Perhaps during your lifetime people will travel, work, and live in the sea.
182. If human beings want to live in the ocean, many human problems will need to be studied first. Some of these problems, similar to those of living in outer space, are pressure, lack of oxygen and weightlessness. Many questions remain unanswered.
183. For example, can our body adjust itself to underwater surroundings? What will happen to our muscles if we live in the water very long? Scientists are searching for answers.
184. Perhaps in the future man will live in the sea or on the sea, away from the crowded and noisy cities on land. The sea has plenty of space, not only for floating communities and parks, but also for storing supplies and for underwater travel.
185. Some scientists believe that ocean living will benefit man in more than physical ways. In the freedom and beauty of the deep sea, man may find new sources of joy.
191. The best high jumper in the world can lift himself only a few feet above the earth. With a balloon or a high－flying jet aircraft he can reach a height of several miles. Only the rocket will enable him to overcome the gravity of the earth and to reach the vast emptiness of space.
192. The pull of gravity depends upon size, or more accurately, upon mass. This is the amount of material in an object. The closer an object is to earth, the greater is the earth’s pull on it. As it gets away from the earth, the strength of the pull weakens.
193. In order to get right away from the earth, rocket will have to fly into space at a speed of seven miles per second. This is called the earth’s escape velocity.
194. The launching of rockets at this speed demands great power, but there is an easy way to do this. We start with a rocket which need not escape completely from the earth. On top of it we place another smaller one and even a third. these can be fired in turn as the first one reaches the end of its flight and falls to earth.
195. As the rocket gets farther into space, the earth’s atmosphere is left behind, and there is less resistance. The earth’s gravity, too, grows weaker and in this way a high speed can be built up. At 25,000 miles per hour our rocket will escape from the earth’s pull and travel wherever it is steered.
1101. Clean air is important to good health. If the air contains impurities, they may be absorbed by our bodies and make us ill. We need clean air, but unfortunately, air pollution is generally present, especially in cities.
1102. Our cities have many factories, which we need to make food products, clothing and many other things. Every year these factories pour millions upon millions of tons of smoke and soot into the air. Power plants that burn coal add greatly to air pollution.
1103. Things made in factories wear out after a while and are thrown away as trash. We burn a lot of trash. More smoke and soot. And then there are the cars made in factories. Once they are out on the street, the cars will take in air and replace it with poison gases. Again, more smoke and soot.
1104. We must take measures to control pollution. No area in the world is completely free of air pollution. Now, more and more people are realizing the importance of clean air. Schools are now teaching about the pollution problem. Industries are beginning to help clean up. They are installing special equipment to clean up their smoke.
1105. Scientists and inventors are trying to develop cleaner engines for cars and trains. Someday we may drive cars that are run by electricity. There is a new kind of paper that will dissolve in water and does not need to be burned. A new kind of glass bottle that will melt in sunlight and disappear is being developed in some countries. The day should come when people can breathe clean air in cities.
1111. Generally, satellite relay stations receive electromagnetic waves from one part of the Earth and then transmit them to another part of the Earth. There are also some satellite relay stations that do a different kind of work. They relay radio waves to the Earth. But they receive the waves that they pass along not from the Earth, but from outer space.
1112. In 1932, an American scientist reported an unexpected and astonishing discovery. He found that the specially designed antenna of his very sensitive radio receiver was picking up radio waves from outside the Earth. In fact the waves seemed to come from outside the solar system.
1113. No one had expected such a thing.This was a surprise. Just where in space do these radio waves come from? What produces them, out there? Scientists called radio－astronomers are busy trying to find out.
1114. To collect there radio waves from outer space giant dish－shaped antennas is one of effective ways . These antennas collect radio waves much as a telescope collects light waves. So they are called radio telescopes. Radio waves from space are now used to explore the Universe, much as light waves are so used.
1115. Do any of these radio waves sweeping through space to the Earth contain a message? Is there, somewhere out in space, intelligent life trying to speak to us? Perhaps you will get answers to these exciting questions in the near future.
1121. A new type of aeroplane engine was invented in 1945. It was much lighter and more powerful than earlier engines, and enabled war planes to fly faster and higher than ever. This type of engine was called the jet engine because it blows a large jet of hot air backwards at high speed.
1122. The first airliner to use the new jet engines was built in Britain and it began carrying passengers in 1952. It had two jet engines and flew much higher than petrol－engined airliners.
1123. At this height, the air is thinner and very cold, and so the aeroplane can cut through the air more easily. There are no clouds to disturb the flight of the airliner, and rain and thunderstorms are far below it. The sky above is a brilliant blue.
1124. Because the air is so cold and thin, the cabin has to be air－conditioned and has to be at normal pressure so that the passengers may eat, read and sleep in comfort. Nowaday, all long distance airliners have jet engines. The modern jet airliners are very big and carry as many as 200 passengers. Some airliners are even bigger; they can carry 350 passengers on two different floors. In this way, air travel can be made much cheaper.
1125. Tomorrow’s airliners will be flying at over twice the speed of today’s airliners. In fact, a new－type airliner has already reached this enormous speed. It can carry passengers in safety and comfort far up in the blue sky.
211. Not long ago, an aeroplane was flying over America. There was a television camera crew on board. Suddenly, out in the night sky, a bright sphere came into view. Everyone on board saw it and everyone thought,: "UFO"---Unidentified Flying Object .The camera crew went into action and started filming.
212. That week people all over the world saw the film of this mysterious light on their television screens. What was it? Was it a spaceship full of visitors from another planet? The captain of the aeroplane and the film crew believed it was. Other observers had many different explanations. Some said it was Venus. Others said it was just a trick of light.
213. However, most scientists now believe that what these people saw was almost certainly the planet Venus. At that time of year it is very bright and easy to see. And from a moving aeroplane it can appear to be moving fast. So far there is no proof that UFOs or spaceships from other planets do exist.
214. These years investigators of UFOs have investigated thousands of sightings--or occasions when people said they saw a UFO. Eighty per cent of these turned out to have a simple explanation.
215. However, it is a good idea to keep an open mind. Scientists in some countries are trying to persuade their governments to support them study UFOs. And they are planning to co-operate internationally on researching and investigating sightings of UFOs. After all, it is quite possible that there is life out there in the universe. And if something is alive, it is quite possible that it will come to visit us..
215. 不过，对这个问题最好是不抱偏见。有些国家的科学家们正在努力劝说各自的政府支持他们的 研究。他们计划在研究和调查不明飞行物的行踪方面进行国际合作。总之,在外层空间很可能存在着生物。而如果真有某种生物存在的话，那就完全有可能来访问我们。
221. An American scientists built an interesting new apparatus which can produce a very strong beam of light. This new light was named "laser". The principle of the laser is that the atoms of a crystal like the ruby crystal can be excited by strong light and can then store this light, amplify it and emit an immensely powerful beam.
222. This light is particularly powerful because it travels in coherent waves, that is, waves which are all the same length and which move in step. For this reason, too, this light consists of only one colour, and not of many colours like sunlight.
223. Light of this strength can be very useful and has already found many different applications in science. One important use of lasers is to measure distances. The astronauts on one Apollo mission set up a reflector on the moon to "catch" laser beams projected from the earth and to return them to our planet.
224. Scientists can calculate the precise distance, when they measure the time the beam takes to go to the moon and come back. Another use of lasers is to measure time. The fact that laser beams are so coherent means that their pulses can be used to divide a single second into fantastically small parts. In fact, pulses of laser light that last only one pico-second have already been produced.
225. Laser beams can also be used in communications. A laser beam travelling through an enclosed tube can carry as much information as 80 million TV channels! Laser, like moving-picture and TV before it, will probably change many aspects of our lives before the end of the twentieth century.
231. From time to time we have to do rather tricky jobs and feel that one of our fingers is getting in the way. We say that we are “all thumbs”, meaning that our fingers seem to be too clumsy for the work. It is possible that on these occasions a specially designed artificial limb would be more efficient.
232. In many countries scientists are studying ways of increasing the power of the human limb, or rather of its muscles. Known as a “man-amplifier”, a machine under development at an American aeronautical laboratory consists of a framework or suit which the operator wears.
233. Every movement he makes is repeated by the steel framework he is wearing, but the power which moves the parts of the frame comes from hydraulic motors. If the operator bends down to pick something up, the machine repeats his movement, lifting as heavy a weight as 450 kilograms in each hand.
234. Another machine with feet and legs is being made, which will enable its user to walk across the countryside very quickly as the stride of this walking machine is much greater than an ordinary man’s. Besides military uses, such devices will obviously be useful to astronauts working on the moon.
235. Just as the operations of a distant unmanned spacecraft circling the moon can be controlled by radio signals, so such devices, properly designed, can be radio-controlled. An astronaut exploring an unknown planet can do part of his exploration without leaving his spacecraft. He can send out a robot which will work on the unknown planet, putting up a permanent observation station or travelling far and wide to collecting rocks and minerals.
233. 操作人员所套着的钢铁框架能重复他的一举一动，不过驱动框架各部件的动力是由液压发动机供给的。 假如操作人员弯腰拾东西，那机器就重复这一动作，每只手提起重达450公斤的重物。
241. There is a science-fiction story in which beings from another planet conquer the earth easily because they have a machine to turn off all the electricity. Well, what would be the effect of such a machine? A century ago, nobody but a few scientists would have observed any difference; most people would simply have continued their lives.
242. Nowday, even the farthest corners of the world are being conquered by electricity, at least by the TV.
243. Most of the trouble of a life without electricity, however, would come to the highly industrialized nations. Many, if not all, of our industries would cease production; all wheels would stop because the motors that power the machines would fail. The world’s transport systems would fall apart without a supply of electricity.
244. Electric trains and trams obviously depend on electric current, but motor vehicles could not be operated, either; they could neither be started (except with a hand-crank)nor would there be any ignition. For the same reason, aeroplanes could not fly.
245. Probably the worst effect would be felt on the world’s communication systems. The telephone, radio, television and radar would become inventions of strictly theoretical interest. The world’s leaders would hold meetings and establish committees to discuss the situation and inform the people; but how would people ever learrn the results of these discussions, with even the printing presses out of service? At the same time, scientists would try to find a way to turn the electricity on again or perhaps to discover a substance that would replace it.
251. Some estimations are too pessimistic, for example, some scientists estimate that at the present rate of use, the world’s known oil deposits could run out in from 10 to 15 years. Even taking into account possible new discoveries of oil deposits, there may be little or no oil left by the end of this century.
252. We need not depend too much on coal or oil for power if we can tap new energy sources. In the long run, there should be no such thing as an energy shortage, because the entire universe consists of energy. Wherever there is matter, there is energy, and all changes of matter involve changes of energy.
253. Making use of the heat in the centre of the earth, for example, is one of man’s endeavours to cope with the energy problem. As you know, the centre of the earth is so hot that all the rock there is liquid. The rock that forms the land and the floor of the sea is a cool crust.
254. This crust is about twenty-five miles thick, and underneath is a thick layer of hot rock, which extends about half way to the centre of the earth. The liquid centre of the earth is thought to have temperatures around 3,700.C.
255. If we drill holes in the crust down to the hot rock below, it would be possible to send water down the holes. The rock would heat the water and turn it into hot steam. The steam would then be forced back up to the surface by the pressure, and could be used to drive turbines to make electricity.
256. This would only be an artificial extension of something that happens naturally in the geysers that are found in Iceland and other regions of the world. It is conceivable that energy from within the earth will be extensively used in the future. There are many other energy sources in store. The problems are connected with harnessing the energy at a reasonable cost so that people in the world can benefit from it.
261. The invention of computers has been one of the greatest advances in modern technology. They are already widely used in industry and in universities, and the time has come when ordinary people can use them as well. Computers are capable of doing extremely complicated work in all branches of learning.
262. They can solve the most complex mathematical problems or put thousands of unrelated facts in order. Because they work accurately and at high speeds, they save research workers years of hard work. This whole process by which machines can be used to work for us has been called automation.
263. Some time ago an expert on automation pointed out that it was a mistake to believe that these machines could “think”. There is no possibility that human beings will be “controlled by machines”. As computers need detailed instructions from human beings in order to be able to operate, they can never “rule the world” by making decisions of their own
264. Computers could be connected with a national network and be used like movable phone. For instance, people going on holiday could be informed about weather conditions; car drivers could be given alternative routes when there are traffic jams.
265. It will also be possible to make tiny translating machines. This will enable people who do not share a common language to talk to each other without much difficulty or to read foreign publications. In hospitals where computers are used, diagnosis becomes quicker and more accurate. Computers can even write out prescriptions. Computers are the most efficient assistants man has ever had and there seems to be no limit to the way in which they can be used to improve our lives.
271. Steam engines were the first to be fitted on aeroplanes,but they were too heavy to be of any use. One such flying machine, made in 1884,consisted of several wings one above the other and was driven by a steam engine. It is said to have risen for a moment off the ground. Another rose, but fell and was damaged.
272. No real success was obtained until the invention of the petrol engine, which is light and powerful enough to be fitted to an aeroplane.
273. At the beginning of this century, two poorly educated young men named Wilbur and Orville Wright made a lot of experiments. They took innense trouble to study the art of flying in gliders so as to be competent in flying their aero-plane. The first flying machine of the Wrights’, made of pieces of wood and cloth, looked too fragile to fly.
274. But in the aeroplane Orville made the first short flight and came down safely. The experiment was repeated three times on the same day. The longest of these flights covered a distance of 852 feet and lasted 59 seconds. The aeroplane was equipped with an engine developing only sixteen horse-power but it the reached a speed of 35 miles an hour.
275. The two brothers continued their experiments on flying in France and astonished all who were watching. By 1908, even the most doubtful of scientists was convinced that a practical flying machine was a reality.
276. The Wright brothers laid the foundation of modern flying. They became world-famous, but they never lost their modesty when honours were showered upon them. They paid little attention to the medals they received from scientific societies. They refused to make public speeches many times.
281. In 1943 Germany’s submarines – the U-boats – were winning the Battle of the Atlantic. Large numbers of U-boats were sending hundreds of Allied ships to the bottom of the ocean. The Atlantic became too dangerous for the Americans to send enough men and war materials across.
282. Suddenly Germany’s U-boat losses doubled in one month. The next month they almost doubled again. In three months nearly 100 U-boats were sunk, mostly by aircraft. What had happened?
283. Once befor, the U-boats had been in trouble because of aircraft. But they soon learned to avoid danger from the air by staying below the surface during the daytime. They had to come up at night to charge their batteries, but that was fairly safe at first. As soon as it became possible for the British Army to fit radar in their coastal command aircraft, there was a change.
284. The Germans began to lose U-boats to these attacks. Because the radar allowed the planes to search large areas of the sea, to find a submarine even at night and in fog, and to attack before the U-boat could go under the water.
285. What about its uses in peace? Radar has made a great difference to the life of a ship’s officer. The radar screen in the wheelhouse shows him every ship that is near him, every piece of land, every buoy, every rock. And he can see them clearly at night or in thick fog.
286. He can measure their ditance from his own ship. And he knows the speed of the other ships and the direction they are travelling in. Radar is a great help to the pilot of an airplane too. Advanced radar systems have made it possible for the pilot to land completely blind in perfect safety.
287. The original radar combined these two units, as its English name RADAR showed: Radio Detection And Ranging. (Detection is finding something as the result of a search; Ranging is finding the exact distance.
291. In 1910, a German meteorologist named Wegener noticed that the edges of South America and Africa looked as if they might fit together like pieces of a jigsaw puzzle. At first he did not want to write about this observation because it seemed unimportant; but then he began to feel that it might mean something.
292. He wasn’t satisfied that this pattern was an accident. Why should such a pattern exist? As he thought about it more, he began to wonder if the two continents had once been parts of a single mass of land that had somehow drifted apare. He wrote, “At first I did not pay attention to the idea because I regarded it as improbable.”
293. Scientists would not take it seriously and laughed at his idea. In the early 1920’s a friend of Wegener’s gave a copy of an article describing Wegener’s idea to a famous geologist to see whether he agreed with it. The geologist must have been enraged. The friend described the geologist’s reaction as the “only occasion on which I saw a man literally foaming at the mouth”.
294. Often a correct idea will take many years before it is widely accepted as true. For example ,in 1543 at a time when most people believed that the sun and the planets circled around the earth .a man named Copernicus suggested that the earth and the other plants revolved around the sun. it took 200 years for this idea to become accepted by most scientists.
295. The same is true of wegener's idea .His idea became the topic of hundreds of scientific articles only sixty years later in the 1970's.In fact ,polls taken of geologists in the late 1960's showed that eighty percent of them agreed with the basic idea of "continental drift".
296. When people finally come up with an unusual idea,they must be very patient in trying to change the minds of others. It might be a correct attitude.
2101. If a young woman of today could go back in time and visit her great--grandmother, she would probably be amazed at the heavy iron pots and pans being used in an old--fashioned kitchen. She would probably be very glad to get back to her own present-day kitchen, with its lightweight equipment, much of which is made of aluminum.
2102. About a hundred and fifty years ago. when it was first produced, aluminum was so difficult to separate from the ores in which it was found that its price was higher than that of gold .
2103. The price remained high until a new process was discovered for refining the metal with the aid of electricity approximately three quarters of a century later. The new method was so much cheaper that aluminum became practical for many purposes, one of the first of which was for making pots and pans.
2104. By mixing it with other metals, scientists have been able to produce a variety of alloys, some of which have the strength of steel but weigh only one third as much. Aluminum is lightweight, rustproof and easily shaped into different forms.
2105. Aluminum is found in the engines of automobiles, in the bodies of trucks, buses, and railroad cars, and in the hulls of boats. It is also used in many parts of airplanes. Today, the uses of aluminum are innumerable. perhaps its most important use is in transportation.
2106. In fact, the huge "airbus" planes would probably never have been produced if aluminum did not exist. By making vehicles lighter in weight, aluminum has greatly reduced the amount of fuel needed to move them. Aluminum is also being used extensively in the building industry in some countries.
2107. Because the source of aluminum is almost inexhaustible, we can expect that more and more uses will be found for this versatile metal. Aluminum is such a versatile metal, it is fortunate that bauxite, which is one of its chief sources, is also one of the earth's most plentiful substances.
2111. Two generations ago petroleum became a revolutionary energy source used to transport man from place to place. Next, it was used to heat homes. more recently, people have begun using it to make clothing, wash dishes and so on. Tomorrow this versatile substance may be called in to help feed man. A look ahead gives petroleum an exciting role in the world of tomorrow.
2112. The century since the first oil well was successfully drilled has been a lively one. But oil's second century promises to be even more exciting. Recently, oil industry chemists, physicists and engineers are carrying out large--scale scientific researches. The fruits of their study can prove to be very astonishing.
2113. To create of synthetic protein from petroleum to help feed men and cattle is high on list of current oil company research projects in some countries .Manufacturing food from oil will some day become a reality.
2114. Already responsible for many plastics, fibers, and synthetic rubber, petrochemicals will play an important role in tomorrow's demand for new things. As the name implies, petrochemicals are chemicals made from petroleum, from the hydrocarbons found in the latter.
2115. By cracking and separating parts, scientists change these hydrocarbons into drip-dry shirts and plastic dishes.
2116. Petrochemicals today account for one-fourth of all the chemicals made; in ten years this amount is expected to double. Petroleum is wonderfully compliant about being broken down and allowing its atoms to be arranged in new ways. There indeed seems to be no end to the tasks that petroleum will be asked to do. People will not stop finding new uses for it.
2116. 当前的石油化工产品占全部已生产的化学产品的四分之一，再过十年这个比例可望增加一倍。石油极易分解，其原子可重新排列。 看来，需要石油承担的任务是无穷无尽的，人们将不断探索它的新用途。
2121. Nowaday the young scientist has a wide choice of subjects in which to specialize. Specialize he must; for each field of study has become so complicated that it requires the complete attention of the trained minds. Each is rapidly advancing, but every advance brings new problems that await solution.
2122. Most scientific progress is the result of careful consideration of work that has already been done. The wonderful world which lies before us today has been built up by hardworking men with clear heads and inventive genius; and those who follow them along life's road will improve on their efforts .
2123. Action or experiment can often end an argument or achieve a breakthrough. It is sometimes necessary to question, and even to disbelieve, some of the statements made by experts.
2124. When men were wondering whether it was possible to reach India by sailing westwards from Europe, and whether there was any land on the other side of the Atlantic ocean, Christopher Columbus decided to act. He gathered some men together, invited them to go on board his three ships, and set out across the dangerous waters of the Atlantic ocean..
2125. He was successful in finding land, but it was not India. The result of his action was that the arguments came to an end
2126. Until the present century no one questioned the statement that the interval of time between two events was the same for every observer. Einstein disposed of this belief. he showed quite clearly that the length of time between two events depends on the velocity of the observer. Any young men who wish to do research must be courageous enough to question old beliefs and do some original thinking about them.
2127. Although we seem to know so much, our ignorance remains profound. Even when we pull an atom to pieces and study its particles, we do not really know what the particles are. We often do not reach the reality behind what we discover, and the more we learn, the better we realize our ignorance.
311. In the long history of man’s inventiveness, discoverers seem to fall into two classes, The first is the ingenious person who sets out to find the solution to a problem. The second is the "lucky" one who appears to stumble upon something by "accident"
312. But we should be clear about what we mean by "accident". For the "accidental" aspect of many great discoveries is that something unusual has happened when there is an observant person present who notices what has happened, and sets to work to find out why.
313. One of “accident discovery”examples is: During the First World War, a well-known expert in metals was asked to investigate the problem of the "pitting" which spoiled gun barrels after they had been fired for a certain length of time. In his research, the first thing that he did was to order a number of barrels to be made of new steel alloys. One of these alloys contained a high percentage of chromium.
314. A gun barrel was made of this new "chromium steel." But the first shot fired through it broke it into a dozen pieces. .So the scraps were thrown on to the waste heap. A week or two afterwards. The expert noticed that among the now rusty scraps of metal, the broken pieces of the chromium steel barrel were as bright as they had been originally. From this "accidental" discovery developed the enormous benefits of "stainless steel".
315. Behind the great rubber industry of today lies a story of one man’s search and of his discovery by "accident" .Rubber in its natural state is hard when cold ,and soft and sticky when heated. Goodyear ,an American ,had been trying to find a way in which rubber could be made hard ,nonsticky, and yet elastic.
316. By chance he dropped a small piece of molded rubber on to a stove and at the same time a piece of sulphur slipped out of his hand .He Scraped the bits of boiling rubber on to a plate .But when it had cooled down, what a different sort of rubber it was! It was cold ,and yet elastic .He had invented---by “accident”---the basic method of preparing rubber for commercial use.
317. Most of discoveries happened when somebody asked himself: "Why? The list of discoveries by “accident”could fill a long book.
321. To hover means to hang or remain in the air over a particular place . The year 1959 saw the first appearance of a real flying ship in the world .The hovercraft can stay up without moving forwards.
322. The hovercraft is a machine that can rise a short distance above the earth: it is round like a saucer ;and it has a short tower in the middle of its upper base.
323. The first full-sized hovercraft weighed several tons, and was raised above the ground by air. Air was driven forcibly downwards through a round hole in the base of the machine by a 450 horse-power engine. The air which was thus driven below the round bottom was directed inwards towards the center, so that a round wall of air pressed towards the middle of the base. this compressed the air already there and the whole machine was raised on a cushion of compressed air
324. But on their first journey ,the pilots on board had to endure the discomfort caused by the spray which came on board .This spray was thrown up from the sea when the air rushed downwards under the hovercraft and struck the water.
325. A high-flying aeroplane flies at heights of 20,000 or 30,000 feet because the air is thinner at great heights ,and therefore offers less resistance to the movement of the aircraft than does the air nearer to the ground then what advantages has the hovercraft over the aeroplane? Since its invention ,the hovercraft has been fully developed and is in constant use.
326. One of the advantages is that the hovercraft can move straight upwards like a helicoptor; it does not require a long runway for the take-off. The hovercraft needs no harbour and no airport .Besides ,it is amphibious
327. Hovercraft consists of an enormous round metal base, with engines, cargo-space and living quarters for the crew on its upper surface. The engines turn fans which drive strong currents of air downwards under the base, thus raising the machine from the ground. It is driven by jets in any direction that the captain chooses.
328. Spray has already proved itself a nuisance to the people on board. besides, during the river journeys, the people who live on the banks near the water may get very wet. if it crosses cultivated fields, it may damage the crops. So the hovercraft also has disadvantages.
331. Black and white television gives us less information than we usually have from normal vision. Nobody who has ever seen good –quality colour television can ever be completely happy with black and white again . Most of us see everything in colour all our lives, and we base quite a large number of our daily actions on colour information. Although the artistic achievements of directors working in black and white have been considerable, there is no doubt that the future is with colour.
332. Scanning was first used in the transmission of pictures by telegraph. A television camera does not look at a scene as a whole in the same way as a film camera; instead, it scans. A light beam looked at a very small part of the picture and translated it into an electric current, which varied in strength according to the amount of light which passed through the picture at that point. It then moved on to the next tiny part of the picture, working across it from left to right, then moving down a line and repeating the process, until it had scanned the whole picture.
333. At the receiving end, the signals were re-translated into a series of dots which, when looked at from a normal reading distance, reproduced the original picture. The television camera also looks at a scene as a series of dots; each dot of light is translated by the camera tube into an electronic signal.
334. A colour transmission contains the same information as a black and white transmission. An additional signal carries the colour information. Three colour-red, green and blue---will, mixed together in the right proportion, give us white light. Change the proportion, or leave out one of the colours, and a range of other colours becomes available: red and green light gives us yellow; green and dark blue gives us a lighter blue; and so on.
335. A colour television camera analyses the light it receives into red, green and blue. In place of the single camera tube of the black and white camera, it has three tubes---one for each of these colours --and the signals produced by them correspond to the amount of each colour.
336. Colour television is really a wonder. Without the use of colour for closed--circuit work there would not be such excellent demonstrations of operations and classroom instructuon in medical schools and monitoring of certain industrial processes in factories as we have today.
337. Today colour receivers are not much more expensive then black and white sets. Nevertheless, many countries are fully committed to colour transmission. How long will it be before black and white sets are found only in museums?
337. 当前 彩色电视接收机不比黑白接收机昂贵的多，尽管如此，许多国家还是完全致力于发展彩色电视传输。还要过多久，黑白电视机才会被送进博物馆呢？
341. It might be a simple decision to take a raincoat when going to school or to delay the start of a football match ,or it might be a more important one to divert an airliner to a fog-free airport. We all use weather information of one kind or another, mostly to make decisions.
342. Millions of decisions like these are made every day ,and to help decision-makers the weathermen can provide information about the past or the future .For the past they have compiled a great mass of statistical and climatological data .on which they can draw to answer all sorts of inquiries; for the future they prepare forecasts.
343. Following are just a few of the activities for which specialized weather services are provided.
Nowadays most aircraft fly high, well above the clouds and weather, but their crews are still vitally interested in landing conditions at their destination, I,e. the cloud base and visibility there .if bad weather is expected the forecaster must be able to suggest another airport within the range of the aircraft where the weather will be suitable for landing.
344. Ships ,whether large or small ,are often at the mercy of the winds and the waves. the large ones can usually ride out the biggest storms, but smaller ones may have to take avoiding action to prevent loss or damage. The weather services help by warning of the coming of strong winds and by predicting their movement.
345. Many long-range lorry operators plan their journeys on the basis of special weather forecasts ;and things such as the degree of refrigeration required for perishable goods during transportation can be determined from temperature forecasts
346. Trains can be help up by frozen points. the icing of electric conductor rails ,and fog, so warnings are provided by weathermen in time for precautionary measures to be taken
347. Farmers have always had a particular interest in the weather because it affects their work and the products of their work at all stages .they like just the right amount of sunshine ,all coming at the right time. perfect weather is not normally provided and the farmer has to make the best of what he gets ,so to plan his operations he relies on the weathermen..
351. To meet the demands of industry, technology, and other sciences, mathematicians have had to invent new branches of mathematics and expand old ones. Never before have so many people applied such abstract mathematics to so great a variety of problems.
352. Applied mathematicians have been coping successfully with the world's problems at a time, curiously enough ,when Pure mathematicians seem almost to have lost touch with the real world. Pure mathematicians don't much care whether mathematics will ever have any practical use. Mathematics has always been abstract.
353. Yet the very abstractness of mathematics makes it useful. By applying its concepts to worldly problems the mathematician can often brush away the details and reveal simple patterns. Celestial-mechanics, for example ,enables astronomers to calculate the positions of the planets at any time in the past or future and to predict the movements of comets .Now this ancient branch of mathematics has suddenly become impressively practical for calculating orbits of earth satellites.
354. Mathematicians who are interested in down-to-earth problems have learned to solve many that were beyond the scope of mathematics only a decade or two ago. They have developed new statistical methods for controlling quality in high-speed industrial mass production
355. They have created an elaborate theory of "information" that enables communications engineers to evaluate precisely telephone, radio, and television circuits.
356. They have analysed the design of automatic controls for such complicated systems as factory production lines and supersonic aircraft. Now they are ready to solve many problems of space travel, from guidance and navigation to flight dynamics of missiles beyond the earth's atmosphere.
357. In designing computer and programming them to carry out instructions, mathematicians have had to develop new techniques. Now that they have electronic computers ,mathematicians are solving problems they would not have dared tackle a few years ago. In a matter of minutes they can get an answer that previously would have required months or even years of calculation.
358. While computers have as yet contributed little to pure mathematical theory, they have been used to test certain relationships among numbers. It now seems possible that a computer some day will discover and prove new mathematical theorems.
361. More than 90 percent of the energy that keeps a city's pulse beating today comes from the combustion of fossil fuels. Even the best coal and purest oil will pollute the air with their manifold combustion products.
362. There are chemical fuels that are clear and smokeless. Hydrogen and ammonia come to mind ;methanol is another possibility. Before too many years have passed, corner gasoline stations may be replaced by ammonia or methanol stations or battery-recharging terminals.
363. Most of us think of ammonia as rather disagreeable. Hydrogen has a reputation for being explosive and dangerous. The chemical and space industries, however ,have tamed both fuels. In recent years. In some ways, anhydrous ammonia is just as safe to handle as gasoline; and liquid hydrogen is becoming common as a high-performance rocket fuel.
364. It is less well known that fully 80 percent of the world's fertilizer requirements are met by synthesizing ammonia from natural gas and steam. Millions of tons of ammonia are consumed annually in agriculture. Consumption increases almost exponentially. Thus, we can imagine ammonia production plants that will "fuel" both farm and city .
365. However, ammonia, methanol or hydrogen will probably never replace petroleum completely. But the wasteful burning of petroleum products seems a great waste of those useful petrochemicals that could otherwise be turned into lubricants, synthetic fabrics, and many other useful products.
366. At present the production of ammonia from electrolytic hydrogen is not economical. If extremely low-cost power were ever to become available from large unclear power plants ,electrolytic hydrogen would become competitive
367. The adoption of an ammonia fuel economy would represent a revolutionary change in the world.That gas station on the corner will not begin dispensing ammonia instead of gasoline for a decade or two. Synthetic sources of energy are ,nevertheless ,an inevitability.
371. Physics can be defined simply As the study of matter and motion. as such ,it is the science that is most basically concerned with uncovering the laws that govern the action of the material world. The laws ascertained by the physicist often become the bases for new sciences.
372. For example ,we will study the way in which Galileo and Newton discovered the basic laws that govern the motion of falling bodies .Today, this knowledge allows us to send probes to the farthest reaches of the solar system and to put men on the surface of the moon--things that Newton could only have dreamed about. In the last century, physicists discovered the laws that govern the motion of fluids. Scientists are now applying these laws to problems as diverse as the flow of protoplasm in a cell and the flow of traffic in city
373. Thus ,when we learn about the way that scientific discoveries were made in the past, we will be learning about things that affect us considerably in our daily lives; when we learn about the kind of research that is going on in the sciences today, we will be getting some insight into things that will be affecting our lives in the future.
374. Of course, physics is only one science among many .in general, we speak of three kinds of "sciences"—physical, biological, and social .The physical sciences (physics, chemistry ,and astronomy) deal with material ,inanimate systems. The biological sciences deal with living systems ,while the social sciences deal with individual or group behavior
375. Nevertheless, physics plays a rather special role among the sciences. As the science that is concerned with understanding the laws of material objects ,it is often intimately involved in the basic workings of the other physical sciences .For example, astronomers have been using the laws of physics to calculate the motions of stars and planets. Chemists have been using the laws of the atom and of heat transfer to deal with reactions they study..
376. Biophysics is concerned with the application of the laws governing atoms and molecules to the large molecules found in living organisms.One of the most exciting developments in modern times has been the birth of biophysics.
381. Miniaturization of equipment is the process by which the overall weight and volume of both components and equipment are reduced.
The trend toward miniaturization of components and equipment of engineering systems since 1940 has been influenced by several factors. First ,and most obviously, the utmost reduction in overall weight and volume is essential to the usefulness and ,in fact, existence of certain types of systems.
382. It is the weight and volume of the payload that have a profound influence on the size of the launching vehicle necessary to put the payload into orbit.Therefor ,aerospace developments have spurred the emphasis toward reduced weight and volume ,particularly in the case of astronautical endeavors.
383. Second ,the concepts of reliability have played an important role in the trend toward miniaturization. Miniaturization of an equipment often results in a reduction of the number of components in that equipment or a reduction in the number of factors influencing the reliability of that equipment, such as the number of soldered connections in electronic components. Reliability increases obviously as the number of components or sources of potential difficulty are reduced.
384. Third, accompanying the strong wish for overall reduction in weight and volume is the need to reduce the power consumption of components and equipments. This need is urgently felt in aerospace devices, in which the weight of the necessary power producing equipment is vital .Power requirements can be equally important for ground-based equipment, for example ,in automatic computers, the use of great number of identical components, all of which have some power requirement, can result in overall equipment that has a very great power requirement .
385. Thus miniaturization and a reduced input power requirement can reduce the need for supporting equipment for heat dissipation, such as radiators or air conditioners. Fourth, the greatly expanding need for electronic assemblies has led to studies of different techniques of automatic production of functionally standardized components. To some extent the smaller the assembly, the more adaptable is its manufacture to automated techniques.
391. Ordinary power stations differ from nuclear power station only in the source of heat .In place of coal or oil-fired boilers, they use a nuclear reactor to provide the heat. The reactor is contained in a giant pressure vessel, a spherical vessel about seventy feet in diameter .
392. Inside the pressuredrum are thousands of graphite blocks ;standing in channels between the blocks are bars of uranium metal an inch or so in diameter ,sheathed in an alloy of magnesium. Heat is developed in the uranium metal by the fission or splitting of some of the atomic nuclei and is carried away by carbon dioxide gas under pressure which is blown through the channels past the uranium bars. The hot carbon dioxide is carried through pipes to tall towers called heat exchangers which contain hundreds of tubes filled with water .
393. The carbon dioxide is cooled and the water heated so that it turns to steam, The steam is carried through pipes to steam turbines which drive the electric generators .The cool carbon dioxide from the heat exchanger is pumped back to the reactor to be heated once more..
394. Much of the complication of the nuclear power station reactor is ,as you see, due to the problems of carrying the heat away and raising steam with it. The simplest sort of reactor is no more than a pile of graphite bricks, each about eight inches square, with channels cut in them in which the uranium metal bars sit .The bars are, in fact ,sheathed in aluminium to prevent the uranium from being oxidized and the radioactive waste products from escaping.
395. A simple "pile" of uranium bars and graphite bricks, if you make it large enough, will "go critical" and start to generate power. This comes about because a chain reaction stars in the uranium bars .The uranium obtained from ores consists of mainly heavy uranium,uranium-238,mixed with about one part in 140 of a slightly lighter kind of uranium-uranium-235.
396. The nuclei of the heavy uranium occasionally split up spontaneously into two fragments of roughly equal size-the process is called fission and the fragments fission products. Efficient as it is, the nuclear power station reactor is dangerous. Therefore the whole reactor is heavily shielded and its operators avoid being exposed to radioactivity.
396. 重铀的原子核有时会自发地分裂成两块大小大致相等的碎块。这个过程称为裂变，而碎块就叫做核裂变物。 核电站反应堆效率尽管很高，但很危险，因此整个反应堆应严加屏蔽，以防操作人员受到辐射伤害。
3101. It has been recognized for a very long while that continued exposure to noise of high intensity would lead to loss of hearing .Less is know about the effects of noise on performance outside the laboratory than is the case with lighting and heating.
3102. There have been occupational deafnesses, for example ,that of the boiler-maker. In recent years ,the development of sensitive and accurate measuring equipment has made it possible to measure the acuity of hearing of any individual at different frequencies .Other equipment has been devised which analyses noise into the various frequencies of the sounds of which it is made up and records the loudness at the different frequencies .High intensity in the higher frequencies does much more damage than high intensity at the low frequencies.
3103. It is probably fairly generally accepted at present that, if the sound pressure level exceeds 85 decibels and the ear is to be subjected to noise at this level continuously, then protection of the ear to reduce sound pressure on it is necessary. This level is somewhere between that created by very heavy street traffic and that caused by the arrival of an underground train in a station.
3104. The following are results of two experiments ,one reported in 1935 and one in 1960. These experiments show that the noise has its effects on performance.
Both were carried out in factories ;both compared the working results of two groups of people on the same kind of work ;in both cases noise was reduced for one group but not for the other.
3105. In 1935,two researchers recorded the results of the wearing of ear-defenders by two weavers. These devices considerably reduced the sound pressure level on the ear, and from records taken over many months it was found that the personal efficiency of those wearing them had increased by 7.5 per cent.
3106. In 1960,two other researchers compared quantity and quality of work of operators of cine-film perforating machines. In one room where the machines were installed, the sound pressure level was reduced by the use of soundabsorbing materials on walls, ceilings and baffles between machines.
3107. Although the quantity of work done by the workers in the experimental group did not differ from that of the control group in rooms where no insulating material had been installed, the quality of their work was significantly higher.