I shall never forget hearing the President's address. 我永远不会忘记聆听总统讲演时的情景.

I forgot to bring my book. 我忘了带书
Don't forget to mail this letter.=Don't forget about mailing this letter. 别忘了寄出这封信.【美】forget 后接动名词与接不定式,意义不同:I forgot to tell her the news.应是「我忘了告诉她这消息」而 I forgot telling her the news.则是「我忘记曾经告诉过她这消息了」.

Let's forget our quarrels. 让我们忘掉我们的争吵吧!
Forget it!=Forget about it! 不用谢了,别再提了,这算不了什么.

Don't forget me to your mother. 别忘了代我问候你母亲
forget one's duties 玩忽职守.

before I forget 趁我还没忘记
He had forgotten about it. 他已把那件事忘了.