need to do ; need doing ; need do

1. need to 作情态动词，通常用于疑问句、否定句、条件句、 whether(if) 名词从句或含否定意义的句子中。如：
I do not see why we need discuss it further.
我看我们没有必要讨论下去了。
That's all settled. It needn't be talked about.
那已全部解决了，没有必要再说了。
He asked me whether he need attend the meeting?
他问我他是否有必要出席这次会议？

2. need 又是实义动词，各种变化和用法与普通实义动词相同。如：
They need a rest after a long walk.
长距离行走后他们需要休息一下。
I need you to work for me, young man!
小伙子，我需要你为工作。

3. need 接动名词主动形式，表示被动意义、这时动名词和主语之间有动宾关系， need doing 可转换为 need to be done 结构，意思相同。如：
My hair needs washing badly. (= My hair needs to be washed badly.)
我的头发非常需要洗一洗。
The garden needs watering. (=The garden needs to be watered.)
花园需要浇水。