后面不带to，表示必要，仅用於否定句及疑问句, 或用於if及whether之後或与hardly﹑ scarcely﹑ no one等连用：

　　You needn't finish that work today.

　　你今天不必把那项工作做完。

　　Need you go yet?

　　No, I needn't.

　　你一定得去吗？

　　我不必去。

　　He wondered whether they need send a deposit.

　　他不知道他们是否得交定金。

　　If she wants anything, she need only ask.

　　她想要什麽，只需说一声就行。

　　I need hardly tell you hat the work is dangerous.

　　无须我说你也知道那工作有危险。

　　Nobody need be afraid of catching the disease.

　　谁都不用害怕能得这种病。

　　二、Need 作实义动词

　　后面要带to，表示需要。

　　I didn't need to go out but I wanted a breath of fresh air.

　　我不一定要出去, 只想吸些新鲜空气。

　　A dog needs to be taken out for a walk every day.

　　狗得每天带出去蹓。

　　Will we need to show our passports?

　　我们要出示护照吗？