5. Astronaut: Any moon, by definition, orbits some planet in a solar system. So, the moons in solar system S4 all orbit the planet Alpha. The astronaut’s conclusion follows logically if which one of the following is assumed? (A) There is only one moon in S4. (B) Every moon in S4 orbits the same planet. (C) Alpha is the only planet in S4. (D) Every planet in S4 is orbited by more than one moon. (E) There is at least one moon that orbits Alpha.
我先分析一下四个选项 A错误条件 B是结论的重复 D文中并未说每个planet,不是必要条件 E从结论推出的必要条件，但和前提没有什么联系 但我不明白为什么C选项是必要条件。我觉得即使存在OTHER PLANETS也不影响什么呀。是不是 one planet can only be orbited by one moon?对了，这也是原文成立的必要条件之一，是吗？ 所以C只是必要条件之一，如果one planet can only be orbited by one moon设为另一个选项F，那么F也是对的。 我的理解对吗？
我把思路写出来，为了保持原汁原味，没作整理
如果我对这道题的理解是对的，那么这道题也太难了，一不小心就会把C给排除掉了 正确的做法是怎样的呢？
15. In the effort to fire a Civil Service employee, his or her manager may have to spend up to $100,000 of tax money. Since Civil Service employees know how hard it is to fire them, they tend to loaf. This explains in large part why the government is so inefficient. It can be properly inferred on the basis of the statements above that the author believes which of the following? I. Too much job security can have a negative influence on workers. II. More government workers should be fired. III. Most government workers are Civil Service employees. (A) I only (B) I and III only (C) II only (D) I, II, and III (E) III only
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发表于 2003-10-21 14:28:00
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