单词 | shadow |
释义 | shadow An area of darkness formed on a surface when an object intercepts the light falling on the surface from a source. In the case of a point source the shadow has a sharply defined outline. If the source has an appreciable size the shadow has two distinct regions; one of full-shadow, called the umbra , the other of half-shadow, called the penumbra (see illustration). ![]() Shadows |
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