Knowing when to leave may beThe smartest thing anyone can learn, go!

知道何时应离开是人能学会的最聪慧的一件事，走吧！

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If our goal was to teach you Physics, you could come to class two hours a week, we would teach you Physics and you would leave class knowing more Physics than when you went in.

如果你每周来上两小时物理课，我们教授物理原理知识，在你离开课室之后，你的物理知识比之前就增加了。

youdao

As Lincoln got on the train that would take him to Washington, he said: "I now leave, not knowing when -- or whether ever I may return.

VOA: special.2009.07.23

Including the songs, l'll Never Fall In Love Again, and Knowing When to Leave, the original cast recording was nominated for a Tony Award and won a Grammy in 1969.

BBC: Hal David, US songwriter, dies at 91