Space is a dangerous place, not only because of meteors(流星), but also because of rays from the sun and other stars. The atmosphere again acts as our protective blanket on the earth. Light gets through, and this is necessary for plants to make the food which we eat. Heat, too, makes our environment suitable to live. 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.

49．According to the first paragraph, the atmosphere is necessary to man because of the following reason EXCEPT________

A．protecting him against the harmful rays from space

B．providing sufficient light for plant growth

C．suppling the heat necessary for human survival

D．screening off the falling meteors

50．We learn from the passage that ________

A．exposure to even tiny amounts of radiation is fatal

B．the effect of exposure to radiation is slow in coming

C．radiation is avoidable in space exploration

D．astronauts in spacesuits needn’t worry about radiation damage

51．The harm radiation that has been done to the Apollo crew members ________

A．is insignificant   B．is enormous   C．seems overestimated  D．remains unknown

52．It can be inferred from the passage that________

A．the Apollo mission was very successful

B．the protection from space radiation is no easy job

C．astronauts may possibly have deformed children or grandchildren

D．radiation is not a threat to well-protected space explorers

53．Which of the following is TRUE?

A．Space is dangerous only because of meteors.

B．Explorers in space have to avoid the damage from radiation

C．We have got effective ways to treat illnesses caused by radiation.

D．The atmosphere doesn’t screen off radiation

Space is a dangerous place, not only because of meteors(流星), but also because of rays from the sun and other stars. The atmosphere again acts as our protective blanket on the earth. Light gets through, and this is necessary for plants to make the food which we eat. Heat, too, makes our environment suitable to live. 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.

49．According to the first paragraph, the atmosphere is necessary to man because of the following reason EXCEPT________

A．protecting him against the harmful rays from space

B．providing sufficient light for plant growth

C．suppling the heat necessary for human survival

D．screening off the falling meteors

50．We learn from the passage that ________

A．exposure to even tiny amounts of radiation is fatal

B．the effect of exposure to radiation is slow in coming

C．radiation is avoidable in space exploration

D．astronauts in spacesuits needn’t worry about radiation damage

51．The harm radiation that has been done to the Apollo crew members ________

A．is insignificant   B．is enormous   C．seems overestimated  D．remains unknown

52．It can be inferred from the passage that________

A．the Apollo mission was very successful

B．the protection from space radiation is no easy job

C．astronauts may possibly have deformed children or grandchildren

D．radiation is not a threat to well-protected space explorers

53．Which of the following is TRUE?

A．Space is dangerous only because of meteors.

B．Explorers in space have to avoid the damage from radiation

C．We have got effective ways to treat illnesses caused by radiation.

D．The atmosphere doesn’t screen off radiation

It is only during the last few years that man has generally realized that in the world of nature a balance exists between all forms of life. No living thing can exist by itself. It is part of a system in which all forms of life are joined together. If we change one part of the nature order, this will almost certainly bring about changes in some other parts.

　　The cutting of forests reduced the supply of oxygen. The killing of weeds and insects by chemicals led to the wide-spread poisoning of animals and birds. The throwing of waste products into the ocean hurt life in the sea, while waste gases changed the chemical balance of the atmosphere and shut out some of the sun’s necessary life-giving rays.

　　And so we could go on adding more examples until in despair(绝望) we might feel like giving up the struggle to control these harmful human activities. Man is very clever at changing the world around him to satisfy his immediate needs, but he is not so clever at looking far ahead, or at thinking about what the future results of his action might be. Man may well destroy himself because of his silly action.

1.The first paragraph tells us that _____.

2.In the second paragraph the examples given are used to prove that _____.

3.The last paragraph suggests that in order to get his immediate benefits(利益) _____.

4.Which of the following is true according to the passage?

It is only during the last few years that man has generally realized that in the world of nature a balance exists between all forms of life. No living thing can exist by itself. It is part of a system in which all forms of life are joined together. If we change one part of the nature order, this will almost certainly bring about changes in some other parts.
The cutting of forests reduced the supply of oxygen. The killing of weeds and insects by chemicals led to the wide-spread poisoning of animals and birds. The throwing of waste products into the ocean hurt life in the sea, while waste gases changed the chemical balance of the atmosphere and shut out some of the sun’s necessary life-giving rays.
And so we could go on adding more examples until in despair(绝望) we might feel like giving up the struggle to control these harmful human activities. Man is very clever at changing the world around him to satisfy his immediate needs, but he is not so clever at looking far ahead, or at thinking about what the future results of his action might be. Man may well destroy himself because of his silly action.

1. 1.

   The first paragraph tells us that _____.

   1. A.
      all living things in nature depend on each other
   2. B.
      everything in nature can’t exist without the help of man
   3. C.
      man has known the importance of the balance of nature for a long time
   4. D.
      no living thing can live naturally
2. 2.

   In the second paragraph the examples given are used to prove that _____.

   1. A.
      all forms of life belong to a system in which all the parts can be changed for one another
   2. B.
      it is only during the last few years that man has generally known the balance of nature
   3. C.
      there are some living things which can exist by themselves without change
   4. D.
      we can’t change one form of life without destroying the balance of nature
3. 3.

   The last paragraph suggests that in order to get his immediate benefits(利益) _____.

   1. A.
      man is always anxious to control his activities within limits
   2. B.
      man is always too eager in planning for distant future
   3. C.
      man often fails to think about their future results of his action
   4. D.
      man often feels that he will have to give up in despair
4. 4.

   Which of the following is true according to the passage?

   1. A.
      Cutting down woods does little harm to human beings.
   2. B.
      Man has to pay much more attention to the future results of his present action.
   3. C.
      Oxygen comes from forests.
   4. D.
      The passage tells us to try our best to get as much as possible immediately.

It is only during the last few years that man has generally realized that in the world of nature a balance exists between all forms of life. No living thing can exist by itself. It is part of a system in which all forms of life are joined together. If we change one part of the nature order, this will almost certainly bring about changes in some other parts.
　　The cutting of forests reduced the supply of oxygen. The killing of weeds and insects by chemicals led to the wide-spread poisoning of animals and birds. The throwing of waste products into the ocean hurt life in the sea, while waste gases changed the chemical balance of the atmosphere and shut out some of the sun’s necessary life-giving rays.
　　And so we could go on adding more examples until in despair(绝望) we might feel like giving up the struggle to control these harmful human activities. Man is very clever at changing the world around him to satisfy his immediate needs, but he is not so clever at looking far ahead, or at thinking about what the future results of his action might be. Man may well destroy himself because of his silly action.
【小题1】The first paragraph tells us that _____.