这本书对我没用，我需要新版本的。

This book is no good to me: I need the new edition.

《牛津词典》

阿兰大声威吓地对我们说，他不会浪费时间讨论这些没用的事情。

In a loud, hectoring tone, Alan told us that he wasn't going to waste time discussing nonsense.

《柯林斯英汉双解大词典》

对改变不了的事情担心也没用。

There's no point in worrying over things you can't change.

《牛津词典》

Well, this is pretty useless, right?

这个是相当没用的，对不？

哈佛公开课 - 计算机科学课程节选