阅读理解
Passage 3
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.
单选题
In the long run, the most insoluble problem caused by population growth on earth will probably be the lack of__________.
单选题
Carl Sagan believes that Venus might be colonized from earth because__________.
【正确答案】
A
【答案解析】此题问的是Carl Sagan认为金星会被征服的原因，属于细节事实题。我们在文章第二段的第一句话“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”(Sagan认为在地球资源完全用尽之前有可能改变金星上的大气，和建造一个与地球差不多大的新世界)中可以找到答案，即原因是“可以改变金星上的大气环境”，正确答案为A。B，C，D三个选项里面所说到的内容均与此段后文所说的内容不相符。
单选题
On Venus there is a lot of
【正确答案】
B
【答案解析】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 onlv a tinv anlount 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 into oxvgen 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。
单选题
Algae are plants that can
【正确答案】
D
【答案解析】此题属于细节事实题。答案可以在第二段的第三句话“Sagan proposes that algae organisms that can live in extremely hot or cold atmospheres and at the same time produce oxygen”中找到，即藻类植物既可以生活在极热或极冷的环境中，同时也可以产生氧气。所以，正确答案为D。