Why get upset just because you got one bad grade?

何必因为一次成绩不好就想不开呢？

《牛津词典》

One bad test can teach you that you will do badly unless you work hard.

一次糟糕的测试能够教会你除非努力学习，否则你还会做得很差。

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Why is one good and one bad?

为什么一个好一个不好？

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Prison spokesman Mark Vernarelli says most teens who visit come to understand what even one bad decision can mean.

VOA: special.2010.11.11

But yet they made one bad choice. One bad choice.

只是他们做了一个错误的选择，仅仅一个而已啊。

普林斯顿公开课 - 人性课程节选

Often, even a whole polis, is paid punishment for one bad man.

整个城邦经常因为一个恶人而受到连坐

耶鲁公开课 - 古希腊历史简介课程节选

And one bad lobbyist, at least one, shouldn't suggest that the entire system is some way corrupt.

NPR: Have Earmarks Really Earned Their Bad Rep?

We had one bad day and to finish four points off the leader is very positive.

BBC: SPORT | Other Sport | Britons land sailing medals

It usually takes several good acts to build, and one bad act to lose.

FORBES: 5 Ways to See If Your Business Integrity is Showing