系动词属于
表语动词,也就是说出现了系动词,这个句型就是主+系+表结构了。
而由谓语动词(又称实义动词)构成的句子则是主+谓+宾结构。
比较大的区别是,当系动词是
be动词(be动词时系动词的一类)时,变否定/疑问句时不需
助动词;而当动词是谓语动词是变否定/疑问句则需要助动词。例如
he
is
a
student.
he
isn't
a
student.
is
he
a
student?
he
likes
sports.
he
doens't
like
sports.
does
he
like
sports?