Lsat-23-4-22.谢谢！

BetterMan · 发表于 2003-8-31 17:38:00

22. When a planetary system forms, the chances that a planet capable of supporting life will be formed are high. The chances that a large planet the size of Jupiter or Saturn will be formed, however, are low. Without Jupiter and Saturn, whose gravitational forces have prevented Earth from being frequently struck by large comets, intelligent life would never have arisen on Earth. Since planetary systems are unlikely to contain any large planets, the chances that intelligent life will emerge on a planet are, therefore, low.
Knowing which one of the following would be most useful in evaluating the argument?
(A) whether all planetary system are formed from similar amounts of matter
(B) whether intelligent species would be likely to survive if a comet struck their planet
(C) whether large comets could be deflected by only one large planet rather than be two
(D) how high the chances are that planetary systems will contain many large comets
(E) how likely it is that planetary systems containing large planets will also contain planets the size of Earth.

答案是D。不理解。原题已经说“Since planetary systems are unlikely to contain any large planets,”，那么再问“how high the chances are that planetary systems will contain many large comets”，是不是没必要？
“行星系统不包含大行星”在这里应该是原题目结论的一个前提吧。可以这么直接反对前提吗？

liu9903 · 发表于 2003-9-2 00:30:00

是大彗星而不是大行星！
有大彗星的概率影响到行星被撞击的概率，从而影响生命存在的可能性

BetterMan · 发表于 2003-9-3 10:07:00

Thanks. 明白了。

Lsat-23-4-22.谢谢！

Lsat-23-4-22.谢谢！

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