I shall never forget the lesson.

我决不会忘记这个教训。

youdao

The accident taught me a lesson I'll never forget.

那事故给我的教训永远也不会忘记。

《牛津词典》

"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。”

youdao

The young consultant who leaked the information learned a lesson she will never forget.

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