1.引导名词性从句,作连接代词,在从句中作主语,宾语,表语.
主语从句：eg:What she did is not yet know.
宾语从 句：I wonder what he's writting to me about.
表语从句：eg:That was what she did this morning on reaching the att
1.引导名词性从句,作连接代词,在从句中作主语,宾语,表语.
主语从句：eg:What she did is not yet know.
宾语从 句：I wonder what he's writting to me about.
表语从句：eg:That was what she did this morning on reaching the att