以下是引用G-CRACKER在2004-10-18 0:12:00的发言：题干中说明实际的估计比原来的估计少，也就是哈雷彗星实际质量比原来预估的要少，欧选C, 可答案是B， 晕晕晕。
16. 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 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.
(D) The reflective properties of the material of which comets are composed vary considerably from comet to comet.
(E) Scientists need more information before they can make a good estimate of the mass of Halley’s comet.
mass总量* 单位反射率= 亮度
亮度不变，原估计的单位反射率下降，则mass总量应该上升，所以，原估计的mass量偏小 | 
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发表于 2004-10-18 00:12:00
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