第1个回答 2008-06-21
首先你要区分从句的概念,定语从句不是名词性从句。
名词性从句分为:主语从句,宾语从句,同位语从句和表语从句。
what可以引导名词性从句,在从句中可做主语、宾语、表语。
which是关系代词,引导定语从句,在从句中可充当主语、宾语、表语。引导定语从句的词分为关系代词(which,that,who,whom,whose,as)关系副词(when,where,why),注意:没有what.
简单点记吧:定语从句放在表示“事物”的名词后面,且关系代词在从句中充当句子成分,用which。如果不是定语从句,就考虑用what。
如:
1.This is the book which I talked about yeasterday.
(which引导定语从句放在名词book后面起修饰作用,which在从句中充当talk about的宾语)
2. This book is what I talked about yesterday.(what引导名词性从句,放在is之后,what 在表语从句(名词性从句)充当talked about的宾语。)