Question

If the population of the Earth keeps on    1.    (increase) at its present rate, there will     2.   (eventual) not be enough resources left to support life on the planet. By the middle of the 21^st century, if present trends continue, we     3.    (use) 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    4.   (necessity) for us to look for open space somewhere else. But    5.    of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem,    6.   , has recently been suggested by an American scientist, Professor Carl Sagan. Sagan believes that    7.    the Earth’s resources are completely   8.    (exhaust), it will be possible to change the atmosphere of Venus and    9.    create a new world almost as large as the Earth itself. The difficulty is that Venus is much hotter than the Earth.   10.    , there is only a tiny amount of water there.

Answer

1.increasing

2.eventually

3.will have used

4.necessary

5.none

6.however

7.before

8.exhausted

9.therefore

10.Besides

【解析】

试题分析：如果地球上的人口持续增长，那么地球上的资源就不能支持那么多的人生活了。有教授认为我们应该改造金星上的空气来制造一个和地球差不多的生存环境以供后世之人的需求。

1. 考查名动词。Keep on doing sth继续做某事，用increasing。

2.考查副词。最终会，修饰形容词enough用副词，用eventually。

3.考查时态。前面if present trends continue是主将从现，主句用将来时，我们将会用完，use up用完，耗尽，用will have used。

4.考查形容词。Make sth necessary某事是必要的，用necessary。

5.考查代词。根据句意 are capable of supporting life at present. 可知没有别的星球是完全适合人类生存的，用none。

6.however考查连词。与上文的没有一个别的星球适合人类生存是转折关系，此句提到了一个可以供人生存的星球，用however。

7.考查连词。在地球的资源都被人用完之前，用before。

8.exhausted考查形容词。耗尽，are 表示被动语态，资源是被人耗尽的，用exhausted。

9.therefore考查连词。表示结果，改变金星的大气层，这样我们才能创造一个和地球一样适合人生存的环境，用therefore。

10.考查连词。另外，金星上只有一点水，与上句是承接关系，用Besides。

考点：考查了一系列时态、连词、副词、动词、形容词等的用法