He learned this lesson the hard way – from his own personal experience.

他惨痛地得到了这一教训–从他自己的亲身经历中得来的。

《柯林斯英汉双解大词典》

Have you prepared this lesson?

你们预习这一课了吗?。

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We must keep this lesson in mind.

我们要记住这个教训。

《新英汉大辞典》

Farmers learn this lesson tragically sometimes when their animals feed on wild plants.

VOA: special.2009.08.25

Now if you can just persuade the English and Portsmouth soccer players of this lesson, I'd be very happy.

现在如果你能让英格兰或者朴茨茅斯球员,学会这个规律的话,我会非常高兴的

耶鲁公开课 - 博弈论课程节选

But bad things will start to happen if I don't mind this lesson of indexing.

但是坏事情将发生,如果我不注意索引的教训。

哈佛公开课 - 计算机科学课程节选

Officials think the markets are strong enough to take this lesson in creditor responsibility.

BBC: Lessons of Cyprus

The Concorde partners learned this lesson 27 years, and lots of taxpayer money, too late.

FORBES: Beware Of The Concorde Fallacy

Everyone from the President of the U.S. on down can benefit from this lesson.

FORBES: Talking Too Much? Maybe Not!