2. 职称英语
  3. Comets do not give off their own light but reflect light from other sources, suc

Comets do not give off their own light but reflect light from other sources, suc

游客2024-01-13  60
问题 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 Hal-ley’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?
选项 A、Some comets are composed of material that reflects 60 times more light per unit of mass than the material of which Hal ley’s comet is composed.
B、Previous estimates of the mass of Halley’s comet which were based 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 arc 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.
答案 B
解析 由题中的论述可知彗星的质量与它们反射的光的多少成比例，当发现单位质量的哈雷彗星的材料实际反射光的强度比以前认为的值低60倍时，在亮度不变的条件下，就可推出目前根据光的强度估算的哈雷彗星的质量就比以前估算的高得多，也就是说以前基于亮度对哈雷彗星的质量的估计太低，所以(B)为正确答案；选项(C)是明显错误的，因为哈雷彗星反射的光的总量是可以被科学家们实际测到的，它是科学家们对彗星质量进行估计的出发点，因此它的值几乎是不变的。(A)、(D)和(E)三选项都不能从段落中合理地推出。
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