什么时候用need,什么时候用need to，什么时候还是情态动词，不会了

一．用作实义动词 作为实义动词
1．need sth.
Eg. Does he need your help ? No,he doesn’t . What do you need? He needs more money.
2. need doing = need to be done
Eg. Our classroom needs cleaning. = Our classroom needs to be cleaned.
3．need to do sth.
Eg. 1). What do we need to take, books or magazines ?
2). Our classroom needs to be cleaned.= Our classroom needs cleaning.
二．用作情态动词. 1.没有人称和数的变化。 2.不能单独充当谓语。情态动词必须与一个实义动词一起构成复合谓语，并且这个实意动词要始终是动词原形。 3．变为否定句时只需在情态动词之后直接加not。 4.变为疑问句时只需将情态动词提到主语的前面。 这是情态动词的共性。
Need he help you? He need not read it again.
---Must we clean the classroom now? ---No, you needn’t.

两个都是“需要做”的意思，意思上区别不大，主要是用法以及否定，下面教你个技巧：
1. need 作情态动词，联想can的用法是：can do 和can't do
就推出来 need do 和need't do
2.need作实义动词，联想go的用法是：go to do 和don't go to do
就推出来 need to do 和don't need to do

need一般在否定句和疑问句中用作情态动词，所以后面接动词原形；在肯定句中一般用作实义动词，后面用to再接动词