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  3. If the population of the Earth goes on increasing at its present rate, there

If the population of the Earth goes on increasing at its present rate, there

游客2025-03-25  4
问题     If the population of the Earth goes on increasing at its present rate, there will eventually not be enough resources left to sustain life on the planet. By the middle of the 21 century, if present trends continue, we will have used up all the oil that drives our cars, for example. Even if scientists develop new ways of feeding the human race, the crowded conditions on Earth will make it necessary for us to look for open space somewhere else. But none of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem, however, has recently been suggested by an American scientist, Professor Carl Sagan.
    Sagan believes that before the Earth’s resources are completely exhausted, it will be possible to change the atmosphere of Venus and so create a new world almost as large as Earth itself. The difficulty is that Venus is much hotter than the Earth and there is only a tiny amount of water there.
    Sagan proposed that algae, organisms that can live in extremely hot or cold atmospheres and at the same time produce oxygen, should be bred in conditions similar to those on Venus. As soon as this has been done, the algae will be placed in small rockets. Spaceships will then fly to Venus and fire the rockets into the atmosphere. In a fairly short time, the algae will break down the carbon dioxide into oxygen and carbon.
    When the algae have done their works, the atmosphere will become cooler but before man can set foot on Venus, it will be necessary for the oxygen to produce rain. The surface of the planet will still be too hot for men to land on it but the rain will eventually fall and in a few years something like Earth will be reproduced on Venus.
    If the experiments are successful, life will become possible there, but it will not be pleasant at first. When they go to Venus, the first colonists will have to take plenty of water with them and get used to days and nights lasting 60 Earth-days. But there will also be some advantages. The colonists will live longer because their hearts will suffer less strain than on Earth. Apart from that, they will be exploiting a new world while those still on Earth are living in closed, uncomfortable conditions. Perhaps it will be the only way to ensure the survival of the human race. [br] It is possible for us to colonize Venus immediately for ______.
选项 A、there is no water there
B、it is too far away for us to go to there
C、it is too hot to support humans life
D、its atmosphere often changes with temperature
答案 C
解析 本题是细节题。该题内容出现在文中第二段。Sagan教授认为：困难在于金星的气温比地球高得太多了，以至那儿仅有非常微量的水。所以人类现在没有办法在金星上生存。所以C选项是正确答案。A选项错误因为金星上还是有微量的水资源，B选项不是理由，因为所有的行星都是遥远的，D选项文中没有提及。
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