三、关系代词的选用[来源:Z&xx&k.Com]
1.指物时必须用that而不用which的情况：
(1)先行词是all，everything，anything，nothing，something，much，little，few，none，the one等不定代词时。
We should hand in all that, we have.
(2)先行词前面有all，every，no，some，any，little，much，few，none，the only，the very，the same，the last以及序数词、形容词最高级等修饰词时。
This is the only, thing that, we can do.
It's the best, film that ,has been made on the subject.
(3)先行词是两个或两个以上分别表示人和物的并列名词或词组时。
We talked about the things and persons that, we saw and met during the trip.
(4)先行词是主句的表语时。
Tom is no longer the boy that, he used to be.
(5)主句以there be开头时。
There is, not much that, we can help.
(6)主句是以who，which开头的疑问句时。
Who ,is the man that, told you the news?
Who, is the man that, you spoke to?
Which ,is the cap that, you have decided to buy?