Place the wire into a non - luminous flame and observe the flame colour.
把线放在不光亮的火焰中,观察火焰的颜色.
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Whether light comes from a luminous or a non - luminous object, it travels in straight lines.
不管是发光体还 是非 发光体发出的光都是以直线传播.
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The moon , for example, does not give off any light of its own. It is non - luminous.
如月亮, 本身不能发出任何光, 它不是发光体.
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