S-11：slip one's mind 忘记
A:I'm sorry I forgot your birthday. I was so busy and the date completely slipped my mind.
A:抱歉，我忘了你的生日，我太忙了，忘了这个日子。
B:Never mind.
B：不要紧。
A:In order to show my regret, I bought a copy of Lu Xun's short stories for you.
A：为了表达我的歉意，我给你买了一套鲁迅短篇小说集。
B:Oh, you shouldn't have done it! It must have cost you a fortune.
B:哦，你不必那么客气，让你破费了。
