1）what=thethingwhich；whatever=anything
Whatyouwanthasbeensenthere.
Whateveryouwantmakesnodifferencetome.
2)who=thepersonthat whoever=anyonewho
（错）Whobreaksthelawwillbepunished.
（错）Whoeverrobbedthebankisnotclear.
（对）Whoeverbreaksthelawwillbepunished.
（对）Whorobbedthebankisnotclear.
3)that和what
当that引导定语从句时，通常用作关系代词，而引导名词性从句时，是个不充当任何成分的连接词。宾语从句和表语从句中的that常可省略。What只能引导名词性从 句，用作连接代词，作从句的具体成分，且不能省略。
Ithink(that)youwilllikethestamps.
Whatweneedismorepractice.
