一道逻辑，蒙了.....请教

月夜圣童 · 发表于 2010-1-9 11:26:37

Comets do not give off their own light but reflect light from other sources, such as the Sun. Scientists estimate the mass of comets by their brightness: the greater a comet’s mass, the more light that comet will reflect. A satellite probe, however, has revealed that the material of which Halley’s comet is composed reflects 60 times less light per unit of mass than had been previously thought.

The statements above, if true, give the most support to which one of the following?

(A) Some comets are composed of material that reflects 60 times more light per unit of mass than the material of which Halley’s comet is composed.

(B) Previous estimates of the mass of Halley’s comet which were base on its brightness were too low.

(C) The total amount of light reflected from Halley’s comet is less than scientists had previously thought.

B和C有什么区别么？说的都是一回事啊？？？正确答案是B.....C错哪了？？

勇士 · 发表于 2010-1-9 11:53:18

因果混乱，科学家是根据反光来判断质量的，所以只可能判断错质量。反光是看到的，而不是根据质量来估计的，怎么可能少估计呢？这个是事后诸葛亮。

evangelia · 发表于 2010-1-9 11:59:58

原文推选项
科学家是通过light per unit of mass的方法来estimate coments的重量的。但是哈雷彗星的材料和其他彗星的材料不一样，这种材料的light per unit of mass比一般彗星材料小60倍。所以以前科学家根据light per unit of mass的方法来estimate哈雷彗星的重量就too low了。选B
C，文中没有说科学家previously thought哈雷彗星的光亮度。文中科学家previously thought的是light per unit mass。认为哈雷彗星和其他彗星一样的light per unit mass.
希望我说清楚了，汗~！

月夜圣童 · 发表于 2010-1-9 13:23:34

多谢两位，明白了，是根据光度推得质量，所以应该是质量错不是光错.....呵呵，大意了...

一道逻辑，蒙了.....请教

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