when you lie with your feet up and your head down. The flowing blood is felt by receptors in the walls of arteries (动脉) in the upper part of the body and in the heart. These receptors send signals to the brain, but the brain reads them incorrectly. To the brain, the signals means the amount of blood in the body has increased, so the brain tells other parts of the body to react to the increase in the blood. For example, the body produces more urine (尿液), resulting in loss of body fluid and salt. At the same time the astronaut has less desire to drink and so does not replace the lost fluid.
As a spacecraft begins to fall back to earth atmosphere, the crew begins to feel gravity. Blood again flows towards the feet and collects there. The heart beats faster in an effort to pump enough blood to the brain. Some crew members may not get enough blood to the brain and the heart beats too fast. They become sick and even lose consciousness as their spacecraft reenters the earth atmosphere. To prevent this, special clothing is invited for astronauts to prevent blood collecting in their legs. They put it on just before the craft reenters the earth’s atmosphere. They also drink about a liter (升) of water and eat some salt to replace the fluid they have lost while in space.
Weightlessness affects the heart and blood vessels in another way. The heart does not work as hard in a weightless environment as it does in an environment of gravity. When the heart works less hard, the heart muscles become weaker. It is replaced by fibrous tissue and fat. 1. If one lies with his feet up and his head down on earth, his
A. heart will pump the blood up to the head. B. blood will flow down towards the feet. C. heart will have to work harder. D. blood will flow up towards the heart. 2. What can we infer from the second paragraph of the passage?
A. The brain reads the signals incorrectly because it tends to go wrong in outer space B. In space an astronaut should drink some water even when he does not feel thirsty. C. In space the amount of water in the body of an astronaut increase.
D. The receptors in the walls of arteries often send wrong signals to the brain.
3. When the spacecraft reenters the earth’s atmosphere some astronauts become sick or even lose consciousness because
A. their brains cannot get enough blood B. their hearts are not strong enough C. their blood collects in their feet D. they begin to feel the gravity again
4. When the spacecraft enter the earth’s atmosphere, the astronauts should do the following except
A. drinking some water. B. eating some salt
C. putting on special clothing D. trying to regain their consciousness
5. After a long time in space, an astronaut’s heart muscles become weaker because A. the heart works too hard under an environment of weightlessness. B. they are completely replaced by fibrous tissue and fat. C. they are short of exercises when the heart works less hard. D. the astronaut’s hard work puts too great a burden on the heart.
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88. What will man be like in the future---in 5,000 or even 50,000 years from now? We can only
make a guess, of course, but we can be sure that he will be different from what he is today. For man is changing slowly all the time.
Let us take an obvious example. Man, even five years ago, was shorter than he is today. Now, on average, men are about three inches taller. Five hundred years is a relatively short period of time, so we may assume that man will continue to grow taller.
Again, in the modern world we use our brain a great deal. Even so, we still make use of only about 20% of the brain’s capacity. As time goes on, however, we shall have to use our brain more and more---and eventually we shall need larger ones! This is likely to bring about a physical change too: the head, in particular the forehead, will grow larger.
Nowadays our eyes are in constant use. In fact, we use them so much that very often they become weaker and we have to wear glasses. But over a very long period of time it is likely that man’s eyes will grow stronger.
On the other hand, we tend to make less use of our arms and legs. These, as a result, are likely to grow weaker. At the same time, however, our fingers will grow more sensitive because they are used a great deal in modern life.
But what about hair? This will probably disappear from the body altogether in course of time because it does not serve a useful purpose any longer. In the future, then, both sexes are likely to be bald!
Perhaps all this gives the impression that future man will not be a very attractive creature to look at! This may well be true. All the same, in spit of all these changes, future man will still have a lot in common with us. He will still be a human being, with thoughts and emotions similar to our own.
1. Future man is likely to be different from us
A. in almost every way B. in quite a few ways C. in great many ways D. in one or two ways
2. The reason for believing that future man will be different is that he A. began to change five years ago B. never stops changing C. never stops growing D. has recently begun to change
3. People’s heads will eventually grow larger. This is because their brains A. will grow faster than at present B. will be in constant use
C. will play an important part D. will need more room than at present 4. Future man will probably A. have bigger eyes B. get weaker eyes C. see better D. have to wear better glasses 5. future man’s hair will A. grow darker B. stop growing completely C. fall out more often D. get longer
89. Some of the most interesting buildings in the world are the pyramids. The pyramids stand
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huge and silent, and in modern days, people look at them and wonder, “Who built them? Why? When? What is inside? How did they do it?”
Thousands of years ago, certain kings of Egypt built the pyramids. They used to build them as tombs. The kings thought the pyramids would help them find life after death. They also wanted the world to remember them as important people. Some pyramids were for queens, but they are less interesting because they are not as big as those of the kings!
The oldest pyramid that we know today is the pyramid near Sakara in Egypt. It is about 5000 years old.
There are many pyramids along the Nile River. The largest is the pyramid of Khufu. It is made of 2,300,000 huge stones, most of them taller than a person. It is about 144 meters high. Inside the pyramid are the burial rooms for the king and queen and long passage ways to these rooms. The rest of the pyramid is made of solid stones.
Workers usually built the pyramids when they had little or no work to do on their farms. To build the pyramid of Khufu, 100,000 men worked for twenty years.
We know there are wonderful treasures in the pyramids. Robbers have dug into some of the pyramids and taken many of these treasures. However, today some of the treasures are in museums.
How did the people of ancient days build the pyramids? How did they carry and lift upwards the huge stones? Each stone fits in with one another so well though they didn’t have our modern machine at all! The ancient art work of Egypt give us the idea of a miracle. Scientists have studied the pyramids, but nobody can say just how they did it. 1. What is this passage mainly about?
A. How ancient tombs were built in Egypt.
B. Some of the most interesting buildings in the world. C. Egyptian Kings and their wives.
D. The oldest pyramid near Sakara in Egypt. 2. People today think the pyramids in Egypt.
A. are reminders of the power enjoyed by the kings. B. are in memory of some important people.
C. will help ancient Egyptian kings find life after death. D. are the most important buildings in the world. 3. Which of the following is true?
A. The pyramid near Sakara is the largest in Egypt.
B. All the stones used to build the pyramid of Khufu are taller than a person. C. It took 100,000 workers and 20 years to build the pyramid of Khufu. D. All the treasures in the burial rooms have been stolen. 4. Why did robbers dig into the pyramids? Because
A. they wanted to see if there were any treasures in them as they thought. B. they wanted to study why each stone fits so well.
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C. they wanted to know how those huge stones were carried and lifted upwards. D. they wanted to steal all the precious things. 5. According to the passage, we...
A. have known a lot about the pyramids. B. know nothing about these ancient tombs. C. can’t say just how these pyramids were built.
D. know quite well how ancient Egyptians built the pyramids.
90. Trees are useful to man in three very important ways: they provide him with wood and
other products; they give him shade; and they help to prevent droughts (干旱) and floods.
Unfortunately, man has not realized that the third of these services is the most important. Two thousand years ago a rich and powerful country cut down its trees to build warships, with which to gain itself an empire(帝国). It gained the empire, but, without its trees, its soil became hard and poor. When the empire fell to pieces, the home country found itself faced by flood and starvation.
Even though a government realizes the importance of a plentiful supply of trees, it is difficult for it to persuade villagers to see this. The villagers want wood to cook their food with; and they can earn money by selling wood. They are usually too lazy to plant and look after the trees. So, unless the government has a good system of control, or can educate the people, the forests will slowly disappear.
This does not only mean that the villagers' children and grandchildren will have fewer trees. The results are even more serious, for where there are trees their roots break the soil
up, allowing the rain to sink in and also bind the soil, thus preventing its being washed away easily. But where there are no trees, the rain falls on hard ground and flows away from the surface, causing flood.
1. That trees can help to prevent droughts and floods is
A. not as important as the other services. B. as important as the other services. C. not important D. more important than any other services. 2. People cut trees down in large numbers so that they found that A. they lost the best friends they had. B. their best friends lost tree. C. their best friends drew quick profit. D. their best friends died.
3. Two thousand years ago, the soil of a rich country became hard and poor, because A. it fell to pieces. B. it was faced with floods.
C. it cut down its trees to build warships. D. it was faced with starvation. 4. It is difficult for a government to persuade the villagers A. to make charcoal B. to realize the importance of trees C. to carry wood to the town D. to cook the food with wood 5. According to the passage we know that trees can A. prevent the rain from falling on the ground. B. cause great floods.
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