which 通常在定语从句中用。在名词性从句中,应该值 哪一个 which one I should choose hasn't been decided. I haven't decided which one I should choose. 定语从句中,which要在从句中充当主语,宾语或者表语,它是关系代词 This is the book which I borrowed from the library.(做borrow的宾语) what 不用于定语从句,在名词性从句中有个特点,就是主句和从句同时缺乏主语,宾语或表语 What I want is a book.( is 少主语,want少宾语) This is what I want.(is少表语,want少宾语)
which是有选择范围的。What没有。 比如你到书店中想买一本英语词典,看到有《牛津》,有《朗文》还有《新英汉》,你不知道该买哪一本,就说: I couldn't decide which dictionary I should buy. 你到水果店里,看到各种各样的水果,你都不知道买什么好了。可以说:I don't know what fruit I should buy.本回答被提问者采纳