Passage One

The dog has always been considered man's best friend. Always noted for being particularly faithful in watching over children, he also has his place by the fireside, in the cow pasture, on the sheep range(放牧区) ,and beside the hunter in forest. He is easy to train, works hard, and often performs astonishing feats. And in the frozen polar regions he was once the principal motive power, before being lately displaced by the plane and helicopter.

Because he howls or whines in the presence of impending death, the dog was once thought to have supernatural powers and believed to be capable of seeing gods and ghosts invisible to men. Actually , the basis for these beliefs lies in the hound's sensibility to people's feelings and his superior hearing ability and sense of smell, which enable him to detect signs hidden from human observation. His record of saving lives is outstanding, for he often gives warning of fire and other dangers not noticed by his master.

The dog's major contribution, however, has been to medical research. Both his diet and his structure are comparable to those of the human being, and so he has been the subject of countless demonstrations and experiments. Open-heart surgery has been made possible largely because of the dog.But his sacrifice has repaid his own species as well by safeguarding it from rabies (狂犬病) , distemper, and other diseases.

Passage Two

Deep inside a mountain near Sweetwater in East Tennessee is a body of water known as the Lost Sea.It is listed by the Guinness Book of World Records as the world's largest underground lake.The Lost Sea is part of an extensive and historic cave system called Craighead Caverns.

The caverns have been known and used since the days of the Cherokee Indian nation. The cave expands into a series of huge rooms from a small opening on the side of the mountain. Approximately one mile from the entrance, in a room called "The Council Room", many Indian artifacts have been found. Some of the items discovered include pottery, arrowheads, weapons, and jewelry.

For many years there were persistent rumors of a large underground lake somewhere in a cave, but it was not discovered until 1905. In that year, a thirteen-year-old boy named Ben Sands crawled through a small opening three hundred feet underground. He found himself in a large cave half filled with water.

Today tourists visit the Lost Sea and ride far out onto it in glass-bottomed boats powered by electric motors. More than thirteen acres of water have been mapped out so far and still no end to the lake has been found. Even though teams of divers have tried to explore the Lost Sea, the full extent of it is still unknown.

Passage Three

Space is a dangerous place ,not only because of meteors but also because of rays from the sun and other stars. The atmosphere again acts as our protective blanket on earth. Light gets through , and this is essential for plants to make the food which we eat. Heat, too, makes our environment endurable. Various kinds of rays come through the air from outer space,but enormous quantities of radiation from the sun are screened off. As soon as men leave the atmosphere they are exposed to this radiation. But their spacesuits or the walls of their spacecraft, if they are inside , do prevent a lot of radiation damage.

Radiation is the greatest known danger to explorers in space. The unit of radiation is called "rem". Scientists have reason to think that a man can put up with far more radiation than 0.1 rem without being damaged;the figure of 60 rems has been agreed on. The trouble is that it is extremely difficult to be sure about radiation damage-a person may feel perfectly well,but the cells of his or her sex organs may be damaged , and this will not be discovered until the birth of deformed(畸形的) children or even grandchildren. Missions of the Apollo flights have had to cross belts of high radiation and , during the outward and return journeys, the Apollo crew accumulated a large amount of rems. So far, no dangerous amounts of radiation have been reported, but the Apollo missions have been quite short. We simply do not know yet how men are going to get on when they spend weeks and months outside the protection of the atmosphere, working in a space laboratory. Drugs might help to decrease the damage done by radiation,but no really effective ones have been found so far.

Passage Four

Mrs. Peters stopped playing the piano when she began to work. She had lived in a very small flat, and there had been no room for a piano. But when she married, she had a new flat which was big enough for one. So she decided to get one and her husband agreed and helped her. She saved some money, and her parents gave her a generous amount of money for her birthday. Then she went to a shop and said, "I'll choose whichever piano does not cost too much and fits into my living room.

When she had paid for the piano, the shop assistant asked her if she would like him to get it tuned(调音) every few months. Mrs. Peters agreed.

A few months later she heard from the shop that a man was coming to tune the piano at ten that morning. Now she had not cleaned the house yet, so it was dusty and untidy. Mrs. Peters hated having even the least amount of dirt, and felt ashamed whenever strange people saw her house like that. So she had to hurry to clean everything carefully. It meant a lot of effort, and it made her hot and tired, but anyhow, by the time the man arrived, everything was finished.

She opened the door, and the man was standing there with a big dog. "Good morning," the man said politely, "Will it disturb you if I bring my dog in, please? I'm blind, and he leads me wherever I go."

Passage Five

It seems so natural to put up an umbrella to keep the water off when it rains. But actually the umbrella was not invented as protection against rain. Its first use was as a shade against the sun!

Nobody knows who first invented it, but the umbrella was used in very ancient times. Probably the first to use it were the Chinese, as early as the eleventh century B. C.

We know that the umbrella was used in ancient Egypt and Babylon as a sunshade. And there was a strange thing connected with its use: it became a symbol of honour and authority. In the Far East in ancient times the umbrella was allowed to be used only by royalty or by those in high office.

In Europe, the Greeks were the first to use the umbrella as a sunshade. And the umbrella was m common use m ancient Greece. But it is believed that the first persons in Europe to use the umbrella as protection against the rain were the ancient Romans.

During the Middle Ages, the use of the umbrella practically disappeared. Then it appeared again in Italy in the late sixteenth century. And again it was considered a symbol of power and authority. By 1680, the umbrella appeared in France, and later on in England.

By the eighteenth century, the umbrella was used against rain throughout most of Europe. Umbrellas have not changed much in style during all this time, though they have become much lighter in weight. It wasn't until the twentieth century that women 's umbrellas began to be made, in a whole variety of colors.

Passage One

There is a popular belief among parents that schools are no longer interested in spelling. No school I have taught in has ever ignored spelling or considered it unimportant as a basic skill. There are, however, vastly different ideas about how to teach it, or how much priority it must be given over general language development and writing ability. The problem is , how to encourage a child to express himself freely and confidently in writing without holding him back with the complexities of spelling.

If spelling becomes the only focal point of his teacher's interest, clearly a bright child will be likely to "play safe". He will tend to write only words within his spelling range, choosing to avoid adventurous language. That's why teachers often encourage the early use of dictionaries and pay attention to content rather than technical ability.

I was once shocked to read on the bottom of a sensitive piece of writing about a personal experience : "This work is terrible ! There are far too many spelling errors and your writing is illegible (难以辨认的) ." It may have been a sharp criticism of the pupil's technical abilities in writing, but it was also a sad reflection on the teacher who had omitted to read the essay, which contained some beautiful expressions of the child's deep feelings. The teacher was not wrong to draw attention to the errors , but if his priorities had centred on the child's idea , an expression of his disappointment with the presentation would have given the pupil more motivation to seek improvement.

Passage Two

It was Ann's first experience of flying. She had always been afraid of heights and so was prepared to be frightened. Only the fact that she was going to meet her son who she had not seen for three years had given her the courage to make the flight.

She sat in her seat, her hands gripping its arms, her seat belt already fastened. The air hostess was talking, telling everyone what to do in case of emergency, showing them where their life-jackets were. The plane was crowded, and every seat was full. From her window seat, getting out in a hurry would be impossible, thought Ann. In any case who would want to get out of a plane in mid-air?

The engines began to shake-the noise increased till it was like a great rushing wind. She looked out to see the runway slip past at astonishing speed. She wanted to cry out-to stop the plane before it left the ground, but she knew she was trapped in this great roaring machine. I must scream, she told herself, and put her hands over her eyes.

There was a strange feeling as if she were going up in a lift. The noise died down. Carefully she opened her eyes. Through the window she saw a great carpet of cloud above, so beautiful that she stared in wonder, hardly turning away from the window till they touched down.

Passage Three

In ancient times wealth was measured and exchanged in things that could be touched: food, tools, and precious metals and stones. Then the barter system was replaced by coins, which still had real value since they were pieces of rare metal. Coins were followed by fiat money, paper notes that have value only because everyone agrees to accept them.

Today electronic monetary systems are gradually being introduced that will transform money into even less tangible forms, reducing it to a series of "bits and bytes", or units of computerized information, going between machines at the speed of light. Already, electronic fund transfer allows money to be instantly sent and received by different banks, companies, and countries through computers and telecommunications devices.

Passage Four

Mr. Smith was a wealthy industrialist, but he was not satisfied with life. He did not sleep well and his food did not agree with him. This situation lasted for some time. Finally, after several sleepless nights, he decided to consult his doctor. The doctor advised a change of surroundings. "Go abroad ," he said. " But I'm not good at foreign language," said Mr. Smith. "It doesn't matter," said the doctor. "It won't hurt you to talk a little less. Go on a voyage. Take plenty of exercise. Try to reduce your weight. Avoid rich food. "

Mr. Smith went to Switzerland. He did not know French or German, and had to communicate through gestures. He attended a physical training course. The instructor made him bend his knees, swing his arms. stretch his neck and shake his head rapidly. He had to lie on the ground and raise his right and left legs alternately. After a time his muscles grew hard and firm. He forgot the financial crisis and the importance of raising the level of production. He even began to notice individual trees and individual birds.

Finally he returned home. But unfortunately his improvement was only temporary. Soon he was a normal businessman again, worried about his property, his profits, his savings, his advancement in a technological society, and things in general.

Passage Five

There was a river with a small town on either side of it. The towns were linked by a bridge.

One day, a hole appeared in the bridge. Both towns agreed that the hole should be mended. However, disagreement came up as to who should mend it. Each town thought that it had a better reason for the other to mend the hole. The town on the right bank said that it was at the end of the road, so the left-bank town should mend the hole. The town on the left bank, on the other hand, insisted that all the traffic came to the right-bank town, so it was in their interest to mend the bridge.

The quarrel went on and on, and so did the hole. The more it went on, the more the hostility between the two towns grew.

One day a man fell into the hole and broke his leg. People from both towns questioned him closely about whether he was walking from the right bank to the left or from the left bank to the right , in order to decide which town should be blamed for the accident. But he could not remember, since he got drunk that night.

Some time later, a car was crossing the bridge and broke an axle(釉) because of the hole. Neither town paid any attention to the accident, as the traveler was not going from one to the other, but was merely passing through. The angry traveler got out of the car and asked why the hole was not mended.

On hearing the reason, he declared, "I'll buy this hole. Who's the owner?"

Both towns at once declared that they owned the hole.

"One or the other, whoever owns the hole must prove it."

"How shall we prove it?" asked both sides.

"That's simple. Only the owner of the hole has the right to mend it. I'll buy the hole from whoever mends the bridge."

People from both towns rushed to do the job while the traveler smoked a cigar and his driver changed the axle. They mended the bridge in no time and asked for the money for the hole.

"What hole?" The traveler looked surprised."I can't see any hole. I've been looking for a hole for several years now. I'm prepared to pay a good price for it, but there's no hole here. Are you pulling my leg or what?"

He got into his car and drove off.

Passage One

Public goods are those commodities from whose enjoyment nobody can be effectively excluded.Everybody is free to enjoy the benefits of these commodities, and one person's utilization does not reduce the possibilities of anybody else' s enjoying the same good.

Examples of public goods are not as rare as one might expect. A flood control dam is a public goods. Once the dam is built, all persons living in the area will benefit-irrespective of their own contribution to the construction cost of the dam. The same holds true for highway signs or aids to navigation. Once a lighthouse is built , no ship of any nationality can be effectively excluded from the utilization of the lighthouse for navigational purposes. National defense is another example. Even a person who voted against military expenditures or did not pay any taxes will benefit from the protection afforded.

It is no easy task to determine the social costs and social benefits associated with public goods.There is no practicable way of charging drivers for looking at highway signs, sailors for watching a lighthouse, and citizens for the security provided to them through national defense. Because the market does not provide the necessary signals , economic analysis has to be substituted for the impersonal judgement of the marketplace.

Passage Two

We can make mistakes at any age. Some mistakes we make are about money. But most mistakes are about people. "Did Jerry really care when I broke up with Helen?" " When I got that great job, did Jim really feel good about it , as a friend? Or did he envy my luck?" When we look back, doubts like these can make us feel bad. But when we look back, it's too late.

Why do we go wrong about our friends or our enemies? Sometimes what people say hides their real meaning. And if we don't really listen closely we miss the feeling behind the words. Suppose someone tells you ,"You're a lucky dog.', That 's being friendly. But "lucky dog" ? There's a bit of envy in those words. Maybe he doesn't see it himself. But bringing in the " dog" puts you down a little. What he may be saying is that he doesn't think you deserve your luck.

“Just think of all the things you have to be thankful for" is another noise that says one thing and means another. It could mean that the speaker is trying to get you to see your problem as part of your life as a whole. But is he? Wrapped up in this phrase is the thought that your problem isn't important. It's telling you to think of all the starving people in the world when you haven't got a date for Saturday night.

How can you tell the real meaning behind someone's words? One way is to take a good look at the person talking. Do his words fit the way he looks? Does what he says agree with the tone of voice? His posture? The look in his eyes? Stop and think. The minute you spend thinking about the real meaning of what people say to you may save another mistake.

Passage Three

Have you ever argued with your loved ones over simple misunderstandings (误解)? Little wonder.We often believe we're more skillful in getting our point across than we actually are, according to Boza Keysar, a professor at the University of Chicago. In his recent study, speakers tried to express their meanings using unclear sentences. Speakers who thought listeners understood were wrong nearly half the time. Here ' s some good advice to reduce misunderstanding:

(1) Don' t trust what you see from the listener. Listeners often nod? look at you or say "uhhuh" to be polite or move the conversation along. But it's easy to consider these as signs of understanding.

(2) Train the editor(编辑) in your head. If you say, "Beth discusses her problems with her husband," it's not clear whether she's talking to her husband or about him. Try instead , " Beth talks to her husband about her problems. " or " Beth talks to others about the problems with her husband. "

(3) Ask listeners to repeat your message. Introduce your request by saying "I want to be sure I said that right." Questions like "How does that sound?" or "Does that make sense?" may also work.

(4)Listen well. When on the receiving end, ask questions to be sure you' re on the same page. After all, it isn't just the speaker's job to make his speech understood.

Passage Four

Almost every family buys at least one copy of a newspaper every day. Some people subscribe to as many as two or three different newspapers. But why do people read newspapers?

Five hundred years ago, news of important happenings-battles lost and won, kings or rulers overthrown or killed-took months and even years to travel from one country to another. The news passed by word of mouth and was never accurate. Today we can read in our newspapers of important events that occur in faraway countries on the same day they happen.

Apart from supplying news from all over the world, newspapers give us a lot of other useful information.There are weather reports, radio, television and film guides, book reviews, stories, and, of course, advertisements. There are all sorts of advertisements. The bigger ones are put in by large companies to bring attention to their products. They pay the newspapers thousands of dollars for their advertising space, but it is worth the money, for news of their products goes into almost every home in the country. For those who produce newspapers, advertisements are also important. Money earned from advertisements makes it possible for them to sell their newspapers at a low price and still make a profit.

Passage Five

All the housewives who went to the new supermarket had one great ambition: to be the lucky customer who did not have to pay for her shopping. For this was what the notice just inside the entrance promised. It said: " Remember, once a week, one of our customers gets free goods. This May Be Your Lucky Day!"

For several weeks Mrs. Edwards hoped, like many of her friends, to be the lucky customer. Unlike her friends, she never gave up hoping. The cupboards in kitchen were full of things which she did not need. Her husband tried to advise her against buying things but failed. She dreamed of the day when the manager of the supermarket would approach her and say : "Madam, this is Your Lucky Day. Everything in your basket is free."

One Friday morning, after she had finished her shopping and had taken it to her car, she found that she had forgotten to buy any tea. She dashed back to the supermarket, got the tea and went towards the cash-desk. As she did so, she saw the manager of the supermarket approach her. "Madam," he said, holding out his hand, "I want to congratulate you! You are our lucky customer and everything you have in your basket is free!"

Passage One

Animals have different ways of protecting themselves against wintertime weather. Some animals grow heavy coats of fur or feathers , while others dig into the ground to find a warm wintertime home.Some animals spend the winter in a deep sleep because by going to sleep they avoid the time of the year when food is scarce and the temperatures are low. Their sleep is known as hibernation .

There is much about hibernation that puzzles scientists. For example , they are wondering how hibernation came into being. Some scientists have explored the possibility that animals release a chemical that starts them hibernating.

One thing that scientists are certain about is that animals hibernate only when it is cold. Hibernation is a seasonal practice.

Some animals that fall into a wintertime sleep are not true hibernators because they spend only a part of the cold season asleep. Bears, for example, can easily be awakened from their winter nap. They are not true hibernators.

Sometimes it is difficult to determine whether a particular animal is a true hibernator. For example , some mice hibernate , but others do not. The same is true of bats. Some of them hibernate.Other do not.

Passage Two

The strange close understanding between twins is a familiar enough phenomenon. Often they seem to understand each other and share each other' s emotions to such an extent that one suspects some kind of thought communication.

What is not so widely known is that this special relationship often acts as brake on twins ' intellectual development. As they are partly isolated in their own private world, twins communicate less with adults than do other children. The verbal ability of a four-year-old twin is typically six months behind that of a non-twin. The problem can be particularly severe in an underprivileged family, a one-parent family for example, where there is little stimulation for children anyway.

Such children, while capable of mutual comprehension in a private language, often remain incomprehensible to outsiders and thus at a severe educational disadvantage. The only solution to the problem. cruel though it may seem, is to separate the twins thus forcing them to acquire ordinary speech helped and guided by sympathetic parents and teachers.

Passage Three

The intelligence test used most often today are based on the work of a Frenchman, Alfred Binet. In 1905, Binet was asked by the French Ministry of Education to develop a way to identify those children in French schools who were too "mentally deficient(不足的)" to benefit from ordinary schooling and who needed special education. The tests had to distinguish those who were merely behind in school from those who were actually mentally deficient.

The items that Binet and his colleague Theophile Simon included on the test were chosen on the basis of their ideas about intelligence. Binet and Simon believed intelligence includes such abilities as understanding the meaning of words; solving problems, and making commonsense judgements. Two other important assumptions also shaped Binet ' s and Simon ' s work : ( 1 ) that children with more intelligence will do better in school and ( 2) that older children have a greater ability than younger children.

Binet' s first test consisted of thirty tasks. They were simple things most children learn as a result of their everyday experiences. The tasks were arranged in groups, according to age. Binet decided which tasks were appropriate for a given age group by giving them first to a large number of children of different ages. If more than half of the children of a given age passed a test, it was considered appropriate for that age group.

Passage Four

How men first learned to invent words is unknown; in other words, the origin of language is a mystery. All we really know is that men, unlike animals, somehow invented certain sounds to express thoughts and feelings, actions and things, so that they could communicate with each other; and that later they agreed upon certain signs, called letters, which could be combined to represent those sounds and which could be written down. Those sounds, whether spoken, or written in letters ,we call words.

The power of words, then, lies in their associations-the things they bring up before our minds. Words become filled with meaning for us by experience; and the longer we live, the more certain words recall to us the glad and sad events of our past; and the more we read and learn, the more the number of words that mean something to us increases.

Great writers are those who not only have great thoughts but also express these thoughts in words which appeal powerfully to our minds and emotions. This charming and telling use of words is what we call literary (文字的) style. Above all, the real poet is a master of words. He can convey his meaning in words which sing like music, and which by their position and association can move men to tears. We should therefore learn to choose our words carefully and use them accurately , or they will make our speech silly and rude.

Passage Five

It is customary for adults to forget how hard and dull and long school is. The learning by memory of all the basic things one must know is a most incredible and unending effort. Learning to read is probably the most difficult and revolutionary thing that happens to the human brain and if you don' t believe that, watch an illiterate adult try to do it. School is not easy and it is not for the most part very much fun, but then, if you are very lucky, you may find a real teacher. Three real teachers in a lifetime is the very best of my luck. My first was a science and math teacher in high school, my second, a professor of creative writing at Stanford, and my third was my friend and partner, Ed Ricketts.

My three had these things in common: They all loved what they were doing. They did not tell; they catalyzed a burning desire to know. Under their influence, the horizons sprung wide and fear went away and the unknown became knowable. But most important of all, the truth, that dangerous stuff, became beautiful and very precious.

I shall speak only of my first teacher because in addition to the other things, she brought discovery.

She aroused us to shouting, book-waving discussions. She had the noisiest class in school and she didn't even seem to know it. We could never stick to the subject. Our speculation ranged the world. She breathed curiosity into us so that we brought in facts or truths shielded in our hands like captured fireflies.

I can tell my son who looks forward with horror to fifteen years of drudgery that somewhere in the dusty dark a magic may happen that will light up the years if he is very lucky.

Passage One

"When one of the doctors criticizes(批评) me,I get defensive: I feel like a child again, being scolded, and I want to explain that I' m not wrong. " says Viola, a nurse. This is a common reaction(反应)to criticism, but not a good one. There are better ways of dealing with criticism.

(1) Try to be objective(客观) . When Sol was criticized by his new employer for not having made a sale , Sol' s reaction was to feel sorry for himself. "I had put everything I had into making that sale . " Sol says , " and I felt that I had failed as a person. I had to learn through experience not to react like that to each failure. "

(2)Take time to cool down. Rather than reacting immediately to criticism, take some time to think over what was said. Your first question should be whether the criticism is fair from the other person' s position. The problem may be a simple misunderstanding of what you did or your reasons for doing it.

(3) Take positive(积极的) action. After you cool down, consider what you can do about the situation. The best answer may be "nothing". "I finally realized that my boss was having personal problems and taking them out on me because I was there , " says Sheila. “His criticisms didn't really have anything to do with my work, so nothing I said or did was going to change them. " In Sheila' s case, the best way to deal with it was to leave her job. However, that' s an extreme reaction. You may simply explain your opinion without expecting an in-depth discussion. You may even decide that the battle isn't worth fighting this time. The key, in any case, is to have a reasonable plan.

Passage Two

Men have traveled ever since they first appeared on the earth.

In primitive times they did not travel for pleasure but to find new places where their herds could feed , or to escape from hostile neighbors , or to find more favorable climates. They traveled on foot. Their journeys were long, tiring, and often dangerous. They protected themselves with simple weapons, such as wooden sticks or stone clubs, and by lighting fires at night and, above all, by keeping together.

Being intelligent and creative, they soon discovered easier ways of traveling. They rode on the backs of their domesticated animals; they hollowed out tree trunks and, by using bits of wood as paddles, were able to travel across water.

Later they traveled, not from necessity, but for the joy and excitement of seeing and experiencing new things. This is still the mam reason why we travel today.

Traveling, of course, has now become a highly organized business. There are cars and splendid roads, express trains, huge ships and jet airliners, all of which provide us with comforts and security. This sounds wonderful. But there are difficulties. If you want to go abroad, you need a passport and a visa, ticket, luggage, and a hundred of other things. If you lose any of them, your journey may be ruined.

Passage Three

One evening Mr. Green was driving home along a lonely country road. He had £1 ,000 in his pocket. At the loneliest part of the road, a man asked for a lift(搭车) . Mr. Green told him to get into the car and continued his driving. When he talked to the man and learned that the man had been in prison for robbery and had broken out of prison two days before, Mr. Green was very worried.

Suddenly he saw a police-car and had a bright idea. He just reached a small town where the speed limit was 30 miles an hour. But he drove the car as fast as it could go. He looked back and saw that the police-car had begun to chase him. After a mile or so the police-car overtook (赶上) him and ordered him to stop. A policeman got out and came to Mr. Green's car. Mr. Green hoped that he could tell the policeman about the escaped robber, but he felt the man had put a gun against his back. The policeman took out his notebook and pencil, saying he wanted Mr. Green ' s name and address. Mr. Green asked to be taken to the police station, but the policeman said, " No, you will have to appear at the police station later. " Mr. Green had to do as the policeman told him. The policeman wrote his name and address down, put his notebook and pencil back in his pocket and gave Mr. Green a talk about dangerous driving. Then Mr. Green started up his car again and drove on.

Just as he reached the suburb of London, the passenger said, "I want to get off here. " Mr. Green stopped the car , the man got out and said, " Thanks for the lift. You've been good to me. This is the least I can do in return. " And he handed Mr. Green the policeman ' s notebook , which he stole while the policeman was talking to Mr. Green.

Passage Four

The banana "tree" is actually not a real tree. This is because there is no wood in the stem(树干) rising above the ground. The stem is made up of leaves growing very close together, one inside the other. The leaves spread out at the top of the stem and rise in the air.

Banana plants need a lot of care and attention. They must be provided with water if the normal rainfall doesn't supply enough. The area around the plants must be kept free of weeds(杂草) and grass.

About nine or ten months after planting , a flower appears on the banana plant. This flower is at the end of a long stalk(茎) , which grows from the base up through the center of the stem and turns downward when it comes out from the top. Small bananas form on this flower stalk as it grows downward. Bananas really grow upside down. As the small bananas form on the stalk , they point down ward, but as they grow they turn and point upward.

Bananas are harvested while they are still green. Even when they are to be eaten where they are grown , they are not allowed to ripen on the plant. A banana that tums yellow on the plant loses its taste.

Passage Five

How can we get rid of garbage? Do we have enough energy sources to meet our future energy needs?

These are two important questions that many people are asking today. Some people think that man might be able to solve both problems at the same time. They suggest using garbage as an energy source,and at the same time it can save the land to hold garbage.

For a long time, people buried garbage or dumped it on empty land. Now , empty land is scarce.But more and more garbage is produced each year. However,garbage can be a good fuel to use. The things in garbage do not look like coal,petroleum , or natural gas ; but they are chemically similar to these fossil fuels. As we use up our fossil-fuel supplies ,we might be able to use garbage as an energy source. Burning garbage is not a new idea. Some cities in Europe and the United States have been burning garbage for years. The heat that is produced by burning garbage is used to boil water. The steam that is produced is used to make electricity or to heat nearby buildings. In Paris, France , some power plants burn almost 2 million metric tons of the city ' s garbage each year. The amount of energy produced is about the same as would be produced by burning almost a half million barrels of oil.

Our fossil fuel supplies are limited. Burning garbage might be one kind of energy source that we can use to help meet our energy needs. This method could also reduce the amount of garbage piling up on the earth.