问题详情：
If the population of the Earth keeps on__61._(increase) at its present rate，there will__62._(event) not be enough resources left to support life on the planet. By the middle of the 21st century，if present trends continue，we__63_(use) up all the oil that drive our cars, for example. Even if scientists develop new ways of feeding the human race, the crowded conditions on Earth will make it__64 (necessity) for us to look for somewhere else. But__65._of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem，__66._， has recently been suggested by an American scientist, Professor Carl Sagan. Sagarn believes that__67._the Earth’s resources are completely__68_(exhaust) ，it will be possible to change the atmosphere of Venus and__69_create a new world almost as large as Earth itself. Something is difficult. Venus is much hotter than the Earth.__70. _， there is only a tiny amount of water there.
【回答】
61.解析: 考查短语keep on doing的用法。
*:increasing
62. 解析: There will not be enough resources的主谓结构是完整的，所以只能用event的副词形式eventually作状语。
*:eventually
63. 解析: 时间状语是by＋将来时间，谓语用将来完成时态。
*:will have used
64. 解析: 考查句型make＋it＋adj.＋for＋sb.＋to do sth.。
*:necessary
65. 解析: 考查理解和代词。根据意思应该是“其他行星中到目前为止还没有一个适合生命的生存。”none of＋复数名词/不可数名词，表示“……中没有一个。”
*:none
66. 解析: 考查上下文理解和行文逻辑。前文说“没办法”，这里说“可能的解决方案”所以用“however”表示转折。
*:however
67. 解析: 考查内容理解和从句。这里应该是“在地球的资源完全枯竭之前”，所以用before。
*:before
68. 解析: 是个及物动词，“耗尽，用完”，这里应该用被动语态。
*:exhausted
69. 解析: 考虑到行文逻辑，这里表示的是结果，因此，so/therefore是最佳措辞。
*:so/therefore
70. 解析: 考查行文逻辑。文章最后两句很明显是解释something is difficult这句话。有两件事是困难的，除了Venus比地球热得多，另一难题是那里的水有限，所以这里用Besides.
*:Besides
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题型：阅读填空
