Life is not a rehearsal or preview. It comes only once.

生活不是彩排或预演，人生只有一次。

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This means you only have toupdate one install when new versions are released and, when it comes toediting source code or uploading plugins, you only have to do thosejobs once.

这意味着当新版本发布，当需要对源码进行编辑或 者上载插件时，你只需要更新一个安装版本，也就是说你可以一次性做完这些工作。

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Summer only comes around once a year, so make it worthwhile!

夏天每年只有一次，所以让它过得有意义吧。

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Milton will only use the word career once in his poetic oeuvre and it comes -- it will come pretty soon, actually, in Sonnet Number Seven.

弥尔顿在他的全部诗歌作品中只用过一次事业这个词,我们马上就会看到，在十四行诗的第七行。

耶鲁公开课 - 弥尔顿课程节选

It only comes around once every four years.

WHITEHOUSE: President Obama and Vice President Biden Honor Iraq Veterans | The White House

But once it comes in, not only do people accept it, they say 'Why didn't we do it before?

BBC: New York's outdoor smoking ban: Will the world follow?