开学课堂英语四级考试阅读练习（10）

　　Sagan believes that before the earths resources are compleetely exhausted it will be possible to change the atmophere of Venus and so create a new world almost as large as earth itself. The difficult is that Venus is much hotter than the earth and there is only a tiny amount of water there.

　　Sagan proposes that algae 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 alge will break down the carbon dioxide into oxygen and carbon.

　　When the algae have done theri work, the atmosphere will become cooler,but befor man can set foot on Venus it will be neccessary 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.

　　1.Inte long run, the most insoluble problem caused by population growth on earth will probably be the lack of ______.

　　a.food

　　b.oil

　　c.space

　　d.resources

　　2.Carl Sagan believes that Venus might be colonized from earth because _____

　　a.it might be possible to change its atmosphere

　　b.its atmosphere is the same as the earths

　　c.there is a good supply of water on Venus

　　d.the days on Venus are long enough

　　3.On Venus there is a lot of ________.

　　a.water

　　b.carbon dioxide

　　c.carbon monoxide

　　d.oxygen

　　4.Algae are plants that can____.

　　a.live in very hot temperatures

　　b.live in very cold temperatures

　　c.manufacture oxygen

　　d.all of the above

　　5. Man can land on Venus only when_______.

　　a.the algae have done their work

　　b.the atmosphere becomes cooler

　　c.thereis oxygen

　　d.it rains there

　　答案：cabdd