1.whatever whoever whichever whenever ---引导名词性从句或状语从句
Whatever he do,he is always careful.
He may do whatever he wants to do
2.no matter what no matterwho no matter which no matter when---只引导状语从句
No matter what he do,he is always careful
=Whatever he do,he is always careful
说明：在状语从句 *ever 可取代no matter *3.what 连接代词，引导名词性从句。例如：Idon't know what he was doing.宾语从句 What he is isn't known.主语从句 The question is what she is.表语从句 I have no idea what he is.同位语从句