On the left, place a blue light; on the right, place a red light.
左边是蓝光；右边是红光。
Wavess of red light are about twice as long as those of blue light.
红色光线的波长约为蓝色波长的两倍。
White light minus blue light is yellow or red in hue.
白光中除去蓝光就呈黄色或红色。
White light minus blue light is yellow or red in hue.
白光中除去蓝光就呈黄色或红色。
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