be动词不就是am is are was were么？为什么还分为系动词和助动词呢？

Question

如题所述

Answer 1

be动词在进行时态和被动语态结构中是助动词，没有意义，只是构成时态和语态
如

He is reading a story book. (is是助动词)

The bridge was built last year.(was是助动词)追答

如下是系动词

He is a student.
He is happy.
They're tired.