光程的物理意义就是光在媒质中通过的几何路程 , 按波数相等折合到真空中的路程.
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牛顿环是利用薄膜干涉的原理,获得相干光的办法是分波面。
A. 对
B. 错
The 12 animal figures of the Chinese calendar exclude ________________
A. the goat.
B. the rabbit.
C. the pig.
D. the cat.
The cat failed to be chosen as one of the 12 animal figures because he was _____________
A. lazy
B. late
C. slow
D. cheated by the rat