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光年是指光在一年时间里所跑过的距离。 Light Year means the distance that light covers in a year. 一光年就是光一年所跑的距离。 And one light year is the distance that travels in one year. 地球离最近的恒星大约为4光年。 The nearest star to earth is about 4 light years away. 观察员最近在...