Sometime early in the next century, human beings will move to Mars. They will live there f

Sometime early in the next century, human beings will move to Mars. They will live there for about a year, and then will be replaced with another group of pioneers. Building the base on Mars will advance our knowledge of the solar system and aid in our understanding of the earth.
We already know that Mars resembles the earth in many aspects: general size, presence of water, length of day, range of temperatures. These resemblances have caused many people to consider a centuries-long project: to terraform Mars. Terraforming means altering a planet’s surface so that Earth’s life forms can survive there. This concept, previously found only in science fiction is now being seriously considered by scientists.
Terraforming Mars is theoretically simple: add nitrogen and oxygen to the atmosphere; pump water to the surface; and add the earth’s plants and animals in the order in which they developed on Earth. But it will take at least 300 years.
Some people think that such a project is too huge for humans to undertake, but there are very good reasons to make the attempt. The earth now contains some 6 billion people, and no one has any idea of how many humans the earth can support. Our very existence and numbers are threatening many other species. We also have had some experience with terraforming our own planet: altering the landscape, the atmosphere and the climate. Currently terraforming earth has become a wiser activity as we try to control global warming, air and water pollution, and preserve some natural living places.
While the possibility of such a project is small, it is not impossible .Even if earth –bound societies come and go in the next 300 years, the project can continue through the work of the Mars settlers without the need for constant backing from the earth.
The future existence of all the people in our world may very well depend upon our ability to terraform Mars.
【小题1】What would be the best title for this passage?A．Terraforming Mars.B．Saving the EarthC．Travelling to Mars.D．A Newly-found Place【小题2】What does the underlined word “altering” mean in the second paragraph?A．Warming.B．Changing.C．Planting.D．Building【小题3】According to the passage the main purpose of terraforming Mars is to .A．do some scientific research workB．find out its similarity to earthC．avoid the dying away of many other speciesD．find on Mars living place for the increasing human beings【小题4】The main reason for causing many people to consider terraforming Mars is that .A．there are some resemblances between Earth and Mars.B．terraforming Mars is theoretically simpleC．we have had some experience with terraforming our own planet: EarthD．the development of science and technology is very rapid【小题5】What’s the author’s attitude towards the project?A．Optimistic.B．NegativeC．Sceptical（怀疑的）D．Objective.A

(答案→)A 解析：本文围绕着人类移民火星而展开论述。首先从火星与地球的相似之处讲到移民火星在理论上的 可行性以及搬迁过程，继而又谈论了人类因人口的急剧增加而向外空发展的必要性。最后分析了人类科技的发展和成就大大增加了使火星适合人类居住和人类移民火星的可能性。【小题1】A主旨大意题。文章首段提出human beings will move to Mars，然后围绕此话题展开论述，所以文章中心应该是将火星地球化问题。所以A选项正确。【小题2】B词意猜测题。由后句so that Earth’s life forms can survive there.可判断为了让地球上的生命能在火星上存活，就要改变火星上的条件以便更适合地球上生命的生长，所以alter应该是改变的意思。【小题3】D推理判断题。由第二段Terraforming means altering a planet’s surface so that Earth’s life forms can survive there.可知使火星地球化的目的是让地球上生命能在火星上存活，故D选项正确。【小题4】A细节理解题。文章第二段Mars resembles the earth in many aspects。。。和 These resemblances have caused many people to consider a centuries-long project: to terraform Mars.，由此可知A选项正确。【小题5】A推理判断题。A 乐观的；B 否定的；消极的；C 怀疑的；D 客观的。从文章倒数第二段While the possibility of such a project is small, it is not impossible可知作者对此事持乐观态度。

我明天再问问老师，叫他解释下这个问题