Do you know why you sleep? You may think it&#039;s because you&#039;re tired. Or perhaps you&#039;ve been told sleep is goo...

题型：阅读选择题类：真题难易度：容易

    Do you know why you sleep? You may think it's because you're tired. Or perhaps you've been told sleep is good for you. Yet no one knows exactly why or how people sleep.
    Until the early 1950s, most scientists thought the body and brain rested during sleep. Then a scientist watched people sleep. He noticed that during periods of between 5 and 30 minutes each, sleepers' eyes made rapid movements, as if they were watching something. He called these periods REM sleep, for Rapid Eye Movement. Periods when sleepers' eyes did not move he called non-REM sleep.
    Whenever the scientist woke people during REM sleep, they were having vivid dreams. Measurements showed that sleepers' pulses（脉搏）went up quickly during REM sleep. Their breathing, heartbeat, and the blood going to the brain also increased. Far from being a time of rest, REM sleep is a time when the body is hard at work. Scientists still don't know the reason for this. Some believe REM sleep makes learning easier. Babies spend a lot of time in REM sleep. Because of this, some scientists believe that REM sleep helps the brain grow. Others think REM sleep is a time for the brain to empty the day's garbage.
    One thing all the scientists agree on is that sleep is necessary. Without enough sleep, people make mistakes. Most major car accidents happen during the early morning hours, when people are sleepiest.

（1）、During REM sleep, a person's breathing and heartbeat ________.

A、stop B、increase C、decrease D、stay the same

（2）、Which word in paragraph（段落）3 means “colorful and lively”?

A、easier B、empty C、vivid D、quickly

（3）、Which paragraph tells what happens when people don't get enough sleep?

A、1 B、2 C、3 D、4

（4）、What is the main idea of the article?

A、REM sleep helps the brain grow. B、REM sleep has been watched and recorded by scientists. C、REM sleep is a time to empty the day's garbage. D、REM sleep is an active time when the body is hard at work.

（5）、You can decide from the article that REM sleep ________.

A、has a restful effect on people B、can be avoided with lots of sleep C、is something that all people experience D、is something that all scientists agree on

举一反三

    The earth is our home; we must take Care of it. This means keeping the land, air and water clean.
    Pollution is a dirty word. To pollute means to make things unfit(不合适的) or unclean to use. Pollution comes in many ways. We see it, smell it, taste it and drink it. Pollution is beginning to threaten(威胁)our health, or happiness and our life.
    Man. has been polluting the earth from the time he first made fire, washed his clothes in the river and threw his waste on the ground. When land was used up or water became dirty. Men moved to another place. At first the problem was not so serious because there was plenty of clean air, land and water. There weren't so many people then and their wants(需求)were fewer. All the dirty things could be absorbed(吸收) by nature and soon covered over(恢复). But this is no longer true. The increase of population(人口增长) and the development of industry have changed that. Man is slowly polluting. his environment.
    Through the use of poison(农药), mall has polluted land! killing the animal. By putting dirty water and chemicals into rivers and lakes we have polluted our drinking water, killing the fish.
    Our increasing population is part of the problem. More people more waste.
    Where is this all to end? Are we turning the world into a big rubbish dump, or is there any hope that we can get rid of(摆脱) the pollution? Luckily, millions of people have been warned of the danger of pollution. Large numbers of people are now working hard to bring pollution under.

In the 13^th century, the famous Indian traveller, Marco Polo, travelled a long way to China. He saw many wonderful things. One of the things he discovered was that Chinese used paper money. In western countries, people did not use paper money until the 15^th century. However, people in China began to use paper money in the 7^th century.
A Chinese man called Cai Lun invented paper almost 2,000 years ago. He made it from wood. He took the wood from trees and made it into paper. He then put these pieces of paper together and made them into a book.
Now paper still comes from trees. We use a lot of paper every day. If we keep on wasting so much paper, there will not be any trees left on the earth. If there are no trees, there will be no paper. Every day, people throw away about 2,800 tons of paper in our city. It takes 17 trees to make one ton of paper. This means that we are cutting nearly 48,000 trees every day. Since it takes more than 10 years for a tree to grow, we must start using less paper now. If we don't, we will not have enough time to grow more trees to take the place of those we use for paper.
So how can we save paper? We can use both sides of every piece of paper, especially when we are making notes. We can also use cotton handkerchiefs（手帕） and paper ones. When we go shopping, we can use fewer paper bags. If the shop assistant does give us a paper bag, we can save it and refuse (拒绝) it later.
Everyone can help to save paper. If we all think carefully, we can help protect trees. But we should do it now, before it is too late.

Air is a colorless, tasteless and invisible（看不见的）gas that is around us. An “empty” drinking glass and an “empty” room, in fact, are not really empty. Each is filled with air. When the glass is filled with water, the water pushes the air out of the glass.
Air, as a gas, has no definite shape, but because it is matter, it takes up space and it has weight. It is easy to prove that air is something that takes up space. Stuff a piece of dry cloth（布）into the bottom of a glass so that it will not fall out when the glass is turned upside down. Push the upside down glass, holding straight up and down, into a jar of water till the glass is completely covered. When the glass is taken out of the water, the cloth is still dry. The air inside the glass shows that it takes up space and keeps the water from coming in.

阅读短文，下列问题

We want to explore and try to better understand the world in which we live. Space exploration is one of the ways.Through the exploration of space, we can begin to unravel the mysteries of our universe, and to better know our living environment.

Space exploration provides us with knowledge about the beginning of our solar system, our own planet and ourselves. It also helps answer the questions that have puzzled us for many years. Solar system exploration is important because it is good for us.

Space technology has become an important part of our daily lives. Some technology uses satellites to communicate. Satellites are also used to examine the changes in the Earth's climate and seas, for weather report and for military. We also use satellites in food production. Because of the use of space technology in crops, fewer and fewer people will suffer hunger.

The space program provides a chance for nations to work together. The cooperation(合作) promotes peace and understanding between governments and their people. Many governments have taken part in the space technology, including the United States, Russia, Japan, the European nations and India. In the near future, other nations will take part in it. In fact, the United States remains the leader in new space technology.

阅读理解

We always think that it's OK for us to leave our plants home during our vacation as plants won't scream like pets, right?

A recent study done by a group of scientists at the Tel Aviv University has discovered that some plants will scream when they are under stress.

The research was carried out on tomato plants and tobacco plants by cutting their stems (茎) and depriving (剥夺) them of water. A microphone was placed 10cm away from them. When their stems were cut, the plants started "screaming" between 20 and 100 kilohertz, and the scientists guess that this scream is probably meant to warn other plants nearby.

When the tomato plants' stems were cut, 25 ultrasonic (超声的) pain sounds were recorded in an hour, and at the same time, 15 ultrasonic pain sounds were recorded from the tobacco plants. When they were deprived of water, the tomato plants recorded even more pain sounds with 35 pain sounds in an hour while the tobacco plants recorded about 11 pain sounds.

The plants also acted differently to different kinds of stresses. For example, the tobacco plants gave out a stronger "scream" when they were deprived of water than when their stems were cut. But plants that were in no immediate (立刻的) danger gave out less than one ultrasonic sound per hour.

The group of scientists said that plants are not as quiet as we had always thought, but in fact their voices are so high-pitched that we just can't hear them.

Last year, another study has found out that plants feel pain when they are touched or hurt and they will give off a terrible smell.

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