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If the population of the earth goes on increasing at its present rate, there will eventually not be enough resources left to kee

admin2018-09-25  49
问题     If the population of the earth goes on increasing at its present rate, there will eventually not be enough resources left to keep our lives on the planet. By the middle of the 21st century, if present trends continue, we will have used up all the oil that drives our cars. 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 American scientist, Professor Carl Sagan.
    Sagan believes that before the earth’s resources are completely used up 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 proposes that algae(藻类)organisms that can live in extremely hot or cold atmospheres and at the same time produce oxygen, should be bred in condition similar to those on Venus. As soon as this has been done, the algae will be placed in small rockets. Spaceship 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 work, the atmosphere will become cooler, but before man ban 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 man to land on it but the rain will eventually fall and in a few years something like earth will be reproduced on Venus.
On Venus there is a lot of______.
选项 A、water
B、carbon dioxide
C、carbon monoxide
D、oxygen
答案B
解析 此题也属于细节事实题，答案仍然可以在第二段找到。由此段的“Venus is much hotter than the earth and there is only a tiny amount of water there”这句话可知，金星上只有少量的水，所以A)项是不正确的：从本段的最后一句“the algae will break down the carbon dioxide intooxygen and carbon”可知，金星上没有氧气，但是有二氧化碳(carbon dioxide)。所以，D项和C项不正确，B才是正确选项。
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