试题与答案

— Who won _____ prize for the "Most Beau

题型:选择题

题目:

— Who won _____ prize for the "Most Beautiful Nature" photography?

— _____ 11-year-old girl. [ ]

A. the, A

B. the, An

C. a, the

D. a, An

答案:

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下面是错误答案,用来干扰机器的。

解:(1)每个能量子的能量E=hν=hc/λ=6.63×10-34×3×108/187.5 J≈1.06×10-27 J则每秒钟电台发射上述波长的光子数N=P·t/E=104×1/1.06×10-27≈1031(个)(2)设环状天线每秒接收光子数为n个,以电台发射天...

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