An episode of major depression may occur only once in a person's lifetime, but more often, it recurs throughout a person's life.

重度抑郁发作可能在一个人的一生中仅出现一次，但更经常的是，它在一个人的一生中反复出现。

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There are cells within your body that are always in the process of division and forming new cells, and sometimes this is for a tissue where cells only have a finite lifetime.

你体内的一些细胞,始终在不断分裂,并生成新的细胞,很多时候,是在一些细胞寿命有限的组织中

耶鲁公开课 - 生物医学工程探索课程节选

So if you get the CD set, not only do you get a wonderful beginning library of classical music but in effect you get a lifetime service contract with it.

所以一旦你买了整套CD,你不仅可以拥有一个古典乐图书馆,而且还可以享受终身服务

耶鲁公开课 - 聆听音乐课程节选

True mastery of the entire complicated process is won only by a lifetime of dedicated work.

UNESCO: Culture

"It's a sort of a once-in-a-lifetime album - only a few of these albums come along in history, " he said.

BBC: Adele tops US chart again in 2012

However, in richer countries if would mean "only a few extra years" on a lifetime of medication.

BBC: Early HIV drugs 'slow virus down'