定語從句放在先行詞後面。定語從句分為限定性定語從句和非限定性定語從句。引導定語從句的詞有關系代詞that、which、who、which、whose和關系副詞where 、when,關系代詞和關系副詞是引導詞,在定語從句中擔當某壹成份。
1、先行詞指物時,關系代詞用that 或which(在句中作主語或賓語)。
如:China is a country which / that has a large population.
The computer game which/ that he is playing is his favorite.
2、先行詞指人時,關系代詞用(who)作主語或賓語,whom (作賓語),whose (作定語),that (作主語或賓語)。如:
The man who is mending the machine has been retired.
This is the policeman who/ whom they were talking about yesterday.
I like the girl whose mother is an actor.
註意:下列情況下關系代詞只用that 而不用which 或who。
3、先行詞是指物的不代詞,如:all, little, few, much, none, anything, nothing, everything等時。如:I didn't understand the words all that he said.
4、先行詞由最高級、序數詞以及any, very, only, all, no, just 等所修飾。如:This is the most beautiful place that I have been to .
5、先行詞既包括人,也包括物。如:They always like to talk about the man and the things that they see on the road.
當主句是以which 或who 開頭的特殊疑問句時。如:who is the man that opened up the lab.
擴展資料必須註意的問題
(1)關系詞作主語時，從句中謂語的數。
(2)註意區別定語從句與強調句。
①定語從句中關系詞作從句成分，復合句。
②強調it無意義，that/who不是引導詞。
③強調it is/was和that/who後如果句子意思講得通則是強調句，講不通則不是。
It is the museum that/which we visited last year。(定語從句)
It was in the hotel that we stayed last night。(強調句)
(3)定語從句與同位語從句的區別。
①定語從句引導詞被稱為關系詞，that充當主語、賓語、表語。有時可省略。
②同位語從句引導詞被叫做連詞，that不能充當任何成分，不可省。
Word came that their army was defeated。(同位語)
We expressed to them our wish that was the same as their。(定語)
(4)關系詞在從句中省略的情況。
①關系詞作賓語，前無介詞時。
②關系詞作表語。
(5)限制性定語從句與非限制性定語從句的翻譯。
(6)關系詞前有介詞或復雜介詞，關系詞只能是which和whom。
百度百科-先行詞