一、用作情态动词

1. 通常用在疑问句、否定句中，或与条件句whether, hardly, nobody等连用。

need+do，否定needn't +do

Need he go so soon? 他这么快就要走吗?

He needn't go．他不必走。

If she wants anything, she need only ask．若她想要什么，只需说一声就行。

2. need引导的疑问句，肯定回答要用must。

—Need I hand it in right now? 我需要现在就交吗?

—Yes, you must．是的，需要现在交。

—No, you needn't．不，不需要现在交。

3. need have done 的否定式或疑问式，表示“本来不必做某事，但事实上却做了”。

You needn't have helped me because I could make it.

你本没必要帮我的，我自己可以做到。

二、用作实义动词

1. 可用于疑问句、否定句和肯定句。

need +to do否定 don't/ doesn't need +to do

Does he need to go so soon? 他这么快就要走吗?

He doesn't need to go．他不必走。

2. need +名词

They need our help. 他们需要我们的帮助。

3. need doing表示被动含义。

The clothes need washing.这些衣服该洗了。

= The clothes need to be washed.

三、用作名词

All our need is just water. 我们所有人都需要水。

We are in need of a good rest. 我们需要好好休息。

There is no need for us to have a rest. 我们没必要休息。

A friend in need is a friend indeed. 患难见真情。