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  3. Astronomers studying a certain kind of supernova (exploding star) were surprised to find the supernovas were fainter than expect

Astronomers studying a certain kind of supernova (exploding star) were surprised to find the supernovas were fainter than expect

admin2020-09-28  74
问题     Astronomers studying a certain kind of supernova (exploding star) were surprised to find the supernovas were fainter than expected. Seeking explanations, they discounted the possibility that cosmic dust might be screening out some of the light, because it would filter out blue light more than red, causing the supernovas to appear redder than they really are. Also, unless spread very smoothly throughout space, the dust would introduce large variations in the measurements. Another possibility is gravitational lensing, the bending of light rays as they skirt galaxies enroute. Such lensing occasionally causes brightening, but most often it contributes to the dimness of distant supernovas. Calculations show, however, that this effect becomes important only for sources more distant than the supernovas studied.
According to the passage, the astronomers rejected gravitational lensing as an explanation for their findings because
选项 A、gravitational lensing can cause supernovas to appear brighter than they really are
B、their calculations showed a negligible effect of gravitational lensing for light rays from distant sources.
C、light rays traveling from the supernovas studied did not have to skirt galaxies.
D、the effect of gravitational lensing on the appearance of supernovas is unpredictable.
E、the supernovas studied were too near for gravitational lensing to have the observed dimming effect.
答案E
解析 根据题干，本题答案应该定位到最后一句。根据最后一句，引力透镜只对更遥远的超新星有效，因此选项E正确。
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本试题收录于： GRE VERBAL题库GRE分类
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