各位大侠，跪求一道费费逻辑题的讲解！个人认为答案有争议

cecilialirui · 发表于 2012-3-30 21:53:43

The axis of Earth’s daily rotation is tilted with respect to the plane of its orbit at an angle of roughly 23 degrees. That angle can be kept fairly stable only by the gravitational influence of Earth’s large, nearby Moon. Without such a stable and moderate axis tilt, a planet’s climate is too extreme and unstable to support life. Mars, for example, has only very small moons, tilts at wildly fluctuating angles, and cannot support life.

If the statements above are true, which one of the following must also be true on the basis of them?

A. If Mars had a sufficiently large nearby moon, Mars would be able to support life.
B. If Earth’s Moon were to leave Earth’s orbit, Earth’s climate would be unable to support life.
C. Any planet with a stable, moderate axis tilt can support life.
D. Gravitational influences other than moons have little or no effect on the magnitude of the tilt angle of either Earth’s or Mars’s axis.
E. No planet that has more than one moon can support life.
答案是选B，但是我想选D。
答案讲解说 only by说明moon是be kept fairly stable 的必要条件。但我认为only by说明That angle can be kept fairly stable与否只受 gravitational influence of Earth’s large, nearby Moon.的影响。而D恰好印证了不受其他因素的影响。其次B中moon 缺少限定词large。
以上分析让我对答案很不理解。求各位大侠讲解，谢谢啦

sdcar2010 · 发表于 2012-3-30 22:18:41

Must-be-true type of question is the easiet of all. All you need is to connecting the dots.

formal logic.

That angle can be kept fairly stable only by the gravitational influence of Earth’s large, nearby Moon. Without such a stable and moderate axis tilt, a planet’s climate is too extreme and unstable to support life.

Premise:

1) Angle/tilt stable --> Moon

2) If tilt/angle not stable --> unstable to support life.

B) No Moon --> angle/tilt not stable --> unstable to support life

sdcar2010 · 发表于 2012-3-30 22:24:53

D is wrong because other celestial bodies might have influence on the angle or tilt. But they are too weak to make the angle unstable.

cecilialirui · 发表于 2012-3-30 22:41:26

really appreciate your explanation. it helps a lot.Thanks

各位大侠，跪求一道费费逻辑题的讲解！个人认为答案有争议

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