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。
温馨提示：
