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：地球资源快要用尽了，太阳系里的金星是否可以开发利用给人类提供一个新的世界呢，科学家正在做相关的研究。

1.increasing 考查短语动词。从固定短语可知，这里用keep on doing，继续做某事，填increasing。

2.eventually考查副词。这里用副词作状语，填eventually，最终。

3.will have used考查时态。If条件句用一般现在时表示将来，主句还应该用将来时，根据句意，如果目前的趋势还将继续的话，我们将会用尽所有的汽油的。填will have used将来完成时。

4.necessary考查形容词。固定搭配make it +adj.+ to do，填necessary 。

5.none考查代词。根据句意，但是在太阳系中没有别的其它星球适合人类居住了，填none，一个也没有。

6.however考查连词作插入语。根据语境，但是，有一个可能的解决措施已经被一个美国科学家提出来。填However表示转折。

7.before考查连词。根据“it will be possible to change the atmosphere of Venus”可知，在地球资源被完全耗尽之前，改变金星的大气层还是有可能的。填before。

8.exhausted考查过去分词。资源被耗尽，用被动语态，填exhausted。

9.therefore考查连词。根据上句，改变金星是可能的，所以创造一个和地球本身一样大的新世界，故填therefore所以。

10.Besides考查连接词。根据语境，金星比地球更热，那里的水资源也很稀少这两句之间是承接关系，所以填Besides另外。