Some changes happen only once in a while, like an eclipse of the moon.

一些变化只有某个时候才会发生，比如月食。

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Year after year and century after century, the moon goes through its cycles of changes.

月亮的盈亏变化一年又一年，一世纪又一世纪，周而复始。（译文根据原句意进行了内涵化引申。） ）

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Year after year and century after century, the moon goes through its cycles of changes.

月亮的盈亏变化一年又一年，一世纪又一世纪，周而复始。（译文根据原句意进行了内涵化引申。） ）

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