定語從句，一個簡單句跟在一名詞或代詞後(先行詞)進行修飾限定，所以叫做定語從句。下面是小編整理的相關內容，歡迎大家閱讀參考！
一、基本概念：
在複合句中，修飾某一名詞或代詞的從句叫定語從句。如：
Do you know the man who spoke at the meeting just now?
That is the house where he lived ten years ago.
定語從句所修飾的詞叫先行詞;定語從句一般用關係代詞或關係副詞來引導，關係詞放在先行詞與定語從句之間起連線作用，同時又作從句中的一個成分。
引導定語從句的關係代詞有：that, who, whom, whose, which;
關係副詞有：when, where, why.
二、關係詞的用法：
(一)關係代詞的用法：
1. 作主語用who, which和that, 如：
He is the man who/that lives next door.
The train which/that has just left is for Shenzhen.
2. 作賓語用whom, who, which, that, 如：
The man (whom/who/that) we have just seen is a famous writer.
Where is the book (which/that) I bought last week?
注：在非正式文體中，用於指人的關係代詞who whom, that 通常可以省略，但在正式文體中通常用whom, 不可省略;用於指物的關係代詞which和that 在非正式文體中也通常省略，但在正式文體中一般不省略。
3. 作定語用whose, 如：
(a) He is the man whose car was stolen last week.
(b) It was a meeting whose importance I did not realize at that time.
注：“whose +名詞中心詞”這一結構在定語從句中既能作主語(如上a句)，又能作賓語(如上b句)。whose 的先行詞常用來指人，但有時也可以用來指具體事物或抽象概念，這時可以與of which 結構互換，詞序是：“名詞+of which”，如：
They came to a house whose back wall had broken down.. (= the back wall of which)
He’s written a book the name of which I’ve completely forgotten. (= whose name)
4. 作表語只用that ，它既可以指人，也可以指物，但時常省略。如：
He is no longer the man that he used to be.
This is no longer the dirty place (that) it used to be.
(二)關係副詞的用法：
指時間，在從句中作時間狀語，它的先行詞通常有：time, day, morning, night, week, year 等。如：
I still remember the time when I first became a college student.
Do you know the date when Lincoln was born?
注：when時常可以省略，特別是在某些句型和某些時間狀語中。如：
Each time he came, he did his best to help us.
But help never stopped coming from the day she fell ill.
e指地點，在從句中作地點狀語。它的先行詞通常有：place, spot, street, house, room,
city, town, country等，如：
This is the hotel where they are staying.
I forget the house where the Smiths lived.
注：where有時也可以省略。如：
This is the place (where) we met yesterday.
3. why指原因或理由，它的先行詞只有reason。如：
That is the reason why he is leaving so soon.
注：why時常也可以省略。如：
That is the real reason he did it.
(三) 使用關係副詞應注意下列幾點：
1. 這三個關係副詞在意義上都相當於一定的介詞+which結構：
when = on (in, at, during…) + which;
where = in (at, on…) + which;
why = for which. 如：
I was in Beijing on the day when (=on which) he arrived.
The office where (=in which) he works is on the third floor.
This is the chief reason why (=for which) we did it.
2. 當先行詞是表時間的time, day等和表地點的place, house等時，一定要注意分析從句的結構，如果缺少主語或賓語時，關係詞應該用which或that, 缺少時間狀語或地點狀語時，才能用when或where，試比較：
I’ll never forget the day when my hometown was liberated.
I’ll never forget the days which/that we spent together last summer.
His father works in a factory where radio parts are made.
His father works in a factory which/that makes radio parts.
3. when和where既可以引導限制性定語從句，也可以引導非限制性定語從句。而why 只
能引導限制性定語從句。
三.限制性定語從句與非限制性定語從句
1.限制性定語從句說明先行詞的.情況，對先行詞起限定作用，與先行詞關係十分密切，不可用逗號隔開，也不可省略，否則全句意義就不完整。如：
This is the telegram which he refers to.
Is there anything (that) I can do for you?
2.非限制性定語從句只是對先行詞作補充說明，沒有限定作用，它與先行詞的關係比較鬆散，因而不是關鍵性的，如果省略，原句的意義仍然完整。這種從句在朗讀時要有停頓，在文字中通常用逗號與主句隔開。如：
This note was left by Tom, who was here a moment ago.
As a boy, he was always making things, most of which were electric.
引導非限制性定語從句的關係詞有：who, whom, whose, which, when 和 where，不可以用that和why。
另外，非限制性定語從句從意義上講，相當於一個並列句，在口語中使用並不普遍，在日常生活中，人們通常用並列句或簡單句來表達。如：
I told the story to John, who later did it to his brother.
= I told the story to John, and he later told it to his brother.
Yesterday I happened to see John, who was eager to have a talk with you.
= Yesterday I happened to see John and he was eager to have a talk with you.
3.兩種定語從句的內涵不同，限制性定語從句具有涉他性，而非限制性定語從句具有 唯一性，這在理解和翻譯時應特別注意。試比較：
All the books there, which have beautiful pictures in them, were written by him.
All the books there that have beautiful pictures in them were written by him.
His brother, who is eighteen years old, is a PLA man. (只有一個)
His brother who is a PLA man is eighteen years old. (不止一個)
4.有時，非限制性定語從句所修飾的不是某一個詞，而是整個主句或是主句中的一個部分，這時一般採用which或as來引導。如：
He passed the exam, which/as he hoped he would.
注：(1)as引導的從句可以放在主句之前，而which引導的從句只能放在主句之後。
They are hollow, which makes them very light.
As is known to all, is a part of China.
(2)從意義上講，which指前面主句的內容;而as指代的是作為一般人都知道的常
識性的東西，因此常譯成“就象… …那樣”。
(3)如果定語從句的內容對主句的內容起消極作用，則用which，而不用as，如：
She stole her friend’s money, which was disgraceful.
He tore up my photo, which upset me.
5.在正式文體中，以the way為先行詞的限制性定語從句通常以in which或 that 引導，如：
The way in which you answered the questions was admirable.
但在非正式文體中，人們通常省略in which或 that :
The way (in which) he spoke to us was suspicious.
I don’t like the way (that) you laugh at her.
