Needless to say I suffered hugely as a manager until I learned the difficult lesson that (as my coach at the time said to me) "You need to find new ways of being important."

不用说，当时我作为一位经理吃了不少苦头，后来才在这些苦头中领悟到(就像当时我的导师对我说的那样)：“你得找到新的方法来体现自己的重要性。”

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"May you never forget this lesson, my son!" said Mr. Prentice, "You now get the secret of success. It lies in never stopping to think about a task being difficult or tiresome, but in going steadily on, with a fixed determination to succeed."

“愿你永远不会忘记这一课，我的儿子！”普伦蒂斯先生说，“你现在得到了成功的秘诀。它在于永远不要停下来去想一项任务多困难或令人厌倦，而是要稳步前进，以坚定的决心取得成功。”

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Interestingly enough, we also learn about compassion through our pets but unfortunately, it is always a very difficult lesson as it is taught near the end of our beloved friends’ lives.

有趣的是，我们同样也从我们的宠物身上学会同情，但是不幸的是这也总是很难的一课，因为当我们学会时，挚爱的朋友的生命也接近尾声。

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In a sense, this is the first difficult lesson of the class.

这是这门课第一个较难的结论

耶鲁公开课 - 博弈论课程节选

I've learned a hard and difficult lesson considering the childhood environment that I was brought up in - not to discriminate against any plant or creature.

BBC: Norfolk - Chris Skinner's wildlife haven

Still, the most important lesson from the trial may be that it is incredibly difficult to tease out the long-term effects of a medicine.

FORBES: Wyeth Lucks Out On Hormone Study

They say they learned that difficult lesson in two of the last three years, when hail destroyed most of their crops.

CNN: farmer plows