定语从句起了形容词的作用，在句中修饰一个名词或代词。被修饰的词叫作先行词，引导定语从句的词叫关系词，它的作用：一是放在先行词与定语从句中间起了连接作用;二是在从句中担当一个成分，并与先行词保持数的一致。

1.关系代词的用法

(1)作主语用who，which和that。例：

He is the man who / that lives next door.

The train which / that has just left is for Shenzhen.

(2)作宾语用whom，who，which，that。例：

The man (whom / who / that) we have just seen is a famous writer.

Where is the book (which / that) I bought last week?

(3)作定语用whose。例：

He is the man whose car was stolen last week.

It was a meeting whose importance I did not realize at that time.

(4)作表语只用that，它既可以指人，也可以指物，但时常省略。例：

He is no longer the man that he used to be.

This is no longer the dirty place (that) it used to be.

2.关系副词

(1)关系副词的用法

① when 指时间，在从句中作时间状语，它的先行词通常有：

time，day，morning，night，week，year

例：I still remember the time when I first became a college student.

Do you know the date when Lincoln was born?

② where指地点，在从句中作地点状语，它的先行词通常有：

place，spot，street，house，room，city，town，country等

例：This is the hotel where they are staying.

I forget the house where the Smiths lived.

③ why指原因或理由，它的先行词只有：

reason

例：That is the reason why he is leaving so soon.

3.连接词只用that的情况

(1)先行词为all，everything，anything，nothing，little，much等不定代词。

(2)先行词被all，any，every，each，much，little，no，some，few等修饰时。

(3)先行词有形容词最高级和序数词修饰时。

(4)先行词既指人又指物时。

(5)先行词被the only，the very修饰时。

(6)句中已经用who或which时，为了避免重复。

4.连接词只用which/ who/ whom的情况

(1)在非限制性定语从句中，只能用which指代物，用who / whom指人。

(2)在由“介词+关系代词”引导的定语从句中，只能用which指物(“介词+ which”一般在定语从句中分别作时间、地点、原因状语，于是“介词+ which”可以分别用when / where / why代替)，whom指人。

(3)先行词本身是that时，关系词用which，先行词为those / one / he时多用who。

5.定语从句注意事项

(1)whose的先行词指物时，可用of which代替，但词序不同，即whose+名词=the +n. + of which=of which + the + n.

He lives in the room whose window faces south.

= He lives in the room，the window of which faces south.

=He lives in the room，of which the window faces south.

(2)当point，situation，case，condition，stage (阶段)等词作先行词表示“情况、境地、场合”等意思时，用where引导定语从句，where在句中作状语。例：

I’ve come to the point where I can’t stand him.

(3)先行词是the way，意为“方式，方法”时，引导定语从句的关系词用that / in which或省略。例：

I didn’t like the way (that / in which) she talked to me.

【典型例题】

--- Where did you see the movie Life of Pi directed by Ang Lee?

---- It was in the cinema _____ I regularly go.

A. which B. that C. where D. what

【答案】C。解析：考查强调句型的省略和定语从句。句意：---你在哪里看的由李安导演的电影“少年派的奇幻漂流记”呢?---是在我经常去的电影院里。此题往往会误认为是强调句型而选B，但是把句子回答完整的话应该是it was in the cinema ____ I regularly go that I saw the movie Life of Pi directed by Ang Lee，是省略了和前面句子的相同成分，即强调句型的省略，所以从结构上判断cinema后面是定语从句，句子为主谓结构，缺少状语，应该选关系副词，四个选项中只有C选项where为关系副词，故选C。