what的同类词有:who、how、when、where、whose、which。
what:
1、引导名词性从句:
I don't understand what he is talking about. (此句中what在名词性从句里做宾语)
It is difficult to decide what should be done first. (此句中what在名词性从句里做主语)
2、引导感叹句:
I can't believe what a beautiful girl she is.
what在从句中充当主语,宾语或表语,意思是“什么”或“所.........的”。
that在从句中不充当成分,无意义。