10/200
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 21st 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 lus 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 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. ｙｎｅｘａｍ．ｃｎ[云南考试网]
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 earth's
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 [云南考试网]www_ynexam_cn
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
10/200答案：cabdd

11/200
What is your favourite colour? Do you like yellow , orange ,red? If you do ,you must be an optimist, a leader, an active person who enjoys life, people and excitement. Do you prefer greys and blues? Then you are probably quiet,shy, and you would rather follow than lead. You tend to be a pessimist. At least, this is what psychologists tell us, and they should know,because they have been seriously studying the meaning of colours preference, as well as the effect that colours have on human beings. They tells us, among other facts,that we do not choose our favourite clour as we grow up----we are born with our preference.If you happen to love brown, you did so, as soon as you opened your eyes, or at least as soon as you could see clearly.
Colours do influence our moods----there is no doubt about it .A yellow room makes most people feel more cheerful and more relaxed than a dark green one; and a red dress brings warmth and cheer to the saddest winter day. On the other hand ,black is depressing. A black bridge over the Thames River, near London, used to be the scene of more suicides than any other bridge in the area ----until it was repainter green.The number of suicide attempts immediately fell sharply ;perhaps it would have fallen even more if the bridge had been done in pink or baby blue.

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