就是what與which的區(qū)別.
還有一個(gè)是what有純名詞性的,如：What he said is wrong.
which只能是由一個(gè)疑問(wèn)句變來(lái)的名詞性從句.
作為疑問(wèn)代詞what和which的區(qū)別是：
后者給定選擇的范圍.前者不限.
如：
Which do you like eat,A or 回答在A或B中選一個(gè).
What do you like to eat?回答是開(kāi)放性的.
兩個(gè)詞都可以作定語(yǔ),后加名詞如：
Which book do you want to buy?
What book do you want to buy?
問(wèn)：什么叫純名詞性
不帶疑問(wèn)性質(zhì)的=名詞+that-定語(yǔ)從句的.
這是我發(fā)現(xiàn)的關(guān)于名詞性從句的一個(gè)細(xì)節(jié).
這種名詞性從句作主語(yǔ)時(shí),是不可以用it來(lái)代替而后置的.
比如：The books that I bought yesterday are very interesting.不能說(shuō)成：It is very interesting the books that I bought yesterday吧?同理,What I bought yesterday is very expensive.不說(shuō)：It is very expensive what I bought yesterday.
但是：What we should do next is still unclear.--> It is still unclear what we should do next.常這么說(shuō).