助动词的作用

1、辅助主动词

2、不能像主动词那样单独作谓语动词

助动词分类

1、基本助动词

be,have,do

2、情态助动词

can/could
may/might
will/would
shall/should
must
ought to
dare/dared
need
used to

3、半助动词

be able to
be going to
be about to
had better
be to
…