need兼有动词/名词两者词性.
1. need作为名词时,初中涉及较少,所以只提供几个常见结构以供参考：
1）in need of... 需要...
如：I'm in need/want of your help.
2）in need 有需要的/困窘的
如：A friend in need is a friend indeed.
3）There be no need of/for sth.
There be no need (for sb) to do sth .是不需要的/不必...
如：There is no need of/for further discussion.
There is no need for you to help him.
2. need作为动词,有两种理解,一是做情态动词,二是做行为动词.
1）need作为情态动词时,一般不用于肯定句,只用于否定句/疑问句.
其后直接加动词原形,没有时态/人称的变化.
其否定句为在need后面直接加not,或使用缩写needn't.
如：I needn't work hard.
其疑问句必须把情态动词need提前,回答也一般借助于need.
如：Need I help you?
2）need作为行为动词时,可用于各种句子,有过去式needed和三单形式needs.
其否定句必须借助于助动词don't/doesn't/didn't等变化.
如：I don't need to work hard.
其疑问句也必须借助于助动词do/does/did等变化.
如：What do you need me to do?
其结构一般有：
need sb/sth 如：I need you. I need your help.
need to do sth 如：I need to work harder.
need sb to do sth 如：I need you to help me.
need doing = need to be done 如：My watch needs repairing. = My watch needs to be repaired
