1.定語從句：修飾壹個名詞或代詞的從句稱為定語從句，壹般緊跟在它所修飾的先行詞後面。2.關系詞：引導定語從句的關聯詞稱為關系詞，關系詞有關系代詞和關系副詞。關系代詞有that, which, who, whom, whose, as等；關系副詞有where, when, why等。關系詞常有3個作用：1，引導定語從句。2，代替先行詞。3，在定語從句中擔當壹個成分。
，名詞，代詞，數詞，分詞，副詞，不定式以及介詞短語來擔任，也可以由壹個句子來擔任．
定語從句是由關系代詞或關系副詞引導的從句，其作用是作定語修飾主句的某個名詞性成分，相當於形容詞，所以又稱為形容詞性從句．
2 定語
編輯本段（壹） 限定性定語從句
1. that既可代表事物也可代表人，which代表事物；它們在從句中作主語或賓語，that在從句中作賓語時常可省略關系詞，which在從句中作賓語則不能省略。而且，如果which在從句中作“不及物動詞＋介詞”的介詞的賓語，註意介詞不要丟掉，而且介詞總是放在關系代詞which的前邊，但有的則放在它原來的位置
2. which作賓語時，根據先行詞與定語從句之間的語義關系，先行詞與which之間的介詞不能丟
3. 代表物時多用which，但在帶有下列詞的句子中用that而不用which，這些詞包括當先行詞是anything, everything, nothing ,few, all, none, little, some等代詞時，或者是由every, any, all, some, no, little, few, much等修飾時等，這時的that常被省略
4. who和whom引導的從句用來修飾人，分別作從句中的主語和賓語，whom作賓語時，要註意它可以作動詞的賓語也可以作介詞的賓語
5. where是關系副詞，用來表示地點的定語從句
6. when引導定語從句表示時間〔註〕值得壹提的是，表示時間“time"壹詞的定語從句只用when引導，有時不用任何關系代詞，當然也不用that引導
By the time you arrive in London, we will have stayed there for two weeks. I still remember the first time I met her. Each time he goes to business trip, he brings a lot of living necessities, such as towers, soap, toothbrush etc.
7. whose是關系代詞，修飾名詞作定語，相當於所修飾成分的前置所有格.它引導的從句可以修飾人和物, 當它引導的從句修飾物體時, 可以與 of which 調換,表達的意思壹樣.
8. 當從句的邏輯主語是some, any, no, somebody, anybody, nobody, something, anything, everything或nothing時，常用there is來引導
There is somebody here who wants to speak to you. 這裏有人要和妳說話。
編輯本段（二）非限定性定語從句
非限定性定語從句的作用是對所修飾的成分作進壹步說明，通常是引導詞和先行詞之間用逗號隔開，將從句拿掉後其他部分仍可成立
1. which引導的非限定性定語從句來說明前面整個句子的情況或主句的某壹部分
2.當先行詞是專有名詞或物主代詞和指示代詞所修飾時，其後的定語從句通常是非限制性的，例如：
Charles Smith, who was my former teacher, retired last year. 查理·史密斯去年退休了，他曾經是我的老師。
My house, which I bought last year, has got a lovely garden. 我去年買的的那幢房子帶著個漂亮的花園。
This novel, which I have read three times, is very touching. 這本小說很動人，我已經讀了三遍。
3.非限制性定語從句還能將整個主句作為先行詞, 對其進行修飾, 這時從句謂語動詞要用第三人稱單數，例如：
He seems not to have grasped what I meant, which greatly upsets me. 他似乎沒抓住我的意思，這使我心煩。
Liquid water changes to vapor, which is called evaporation. 液態水變為蒸汽，這就叫做蒸發。
4. 有時as也可用作關系代詞
5. 在非限定性定語從句中，不能用關系副詞why和關系代詞that，而用who, whom代表人，用which代表事物.；
編輯本段（三）關系代詞引導的定語從句
1.who指人，在從句中做主語
(1) The boys who are playing football are from Class One.
(2) Yesterday I helped an old man who lost his way.
2. whom指人，在定語從句中充當賓語，常可省略。
(1) Mr. Liu is the person (whom) you talked about on the bus.
(2) Mr. Ling is just the boy whom I want to see.
註意：關系代詞whom在口語和非正式語體中常用who代替，可省略。
(3) The man who/whom you met just now is my friend
3.which指物，在定語從句中做主語或者賓語，做賓語時可省略
(1) Football is a game which is liked by most boys.
(2) This is the pen (which) he bought yesterday.
如果在從句中做賓語,就用whom或who.比如: He is the man whom/who I talk to.
如果是在從句中作主語就只能用who.比如: He is the man who has an English book.
4. that指人時，相當於who或者whom；指物時，相當於which。
在定語從句中做主語或者賓語，做賓語時可省略。
(5) The number of the people that/who come to visit the city each year rises one million.
(6) Where is the man that/whom I saw this morning?
5. whose通常指人，也可指物，在定語從句中做定語
(1) He has a friend whose father is a doctor.
(2) I once lived in a house whose roof has fallen in.whose指物時，常用以下結構來代替
(3) The classroom whose door is broken will soon be repaired.
(4) The classroom the door of which is broken will soon be repaired.
(5) Do you like the book whose cover is yellow?
(6) Do you like the book the color of which is yellow?
編輯本段（四）註意
介詞+關系代詞引導的定語從句關系代詞在定語從句中做介詞賓語時
從句常由介詞+關系代詞引導
(1) The school (that/which) he once studied in is very famous.
(2) The school in which he once studied is very famous.
(3) Tomorrow I will bring here a magazine (that/which) you asked for.
(4) Tomorrow I will bring here a magazine for which you asked.
(5) We’ll go to hear the famous singer (whom/that/who) we have often talked about.
(6) We’ll go to hear the famous singer about whom we have often talked.
註意：1. 含有介詞的動詞短語壹般不拆開使用，如：look for, look after, take care of等
(1) This is the watch which/that I am looking for. (T)
(2) This is the watch for which I am looking. (F)
2. 若介詞放在關系代詞前，關系代詞指人時用whom，不可用who或者that；指物時用which，不能用that；關系代詞是所有格時用whose
(1) The man with whom you talked is my friend. (T)
(2) The man with that you talked is my friend. (F)
(3) The plane in which we flew to Canada is very comfortable. (T)
(4) The plane in that we flew in to Canada is very comfortable. (F)
3. “介詞+關系代詞”前可有some, any, none, both, all, neither, most, each, few等代詞或者數詞
(1) He loved his parents deeply, both of whom are very kind to him.
(2) In the basket there are quite many apples, some of which have gone bad.
(3) There are forty students in our class in all, most of whom are from big cities.
編輯本段（五）關系副詞引導的定語從句
1. when指時間，在定語從句中做時間狀語
(1) I still remember the day when I first came to the school.
(2) The time when we got together finally came.
2. where指地點，在定語從句中做地點狀語
(1) Shanghai is the city where I was born.
(2) The house where I lived ten years ago has been pulled down.
3. why指原因，在定語從句中做原因狀語
(1) Please tell me the reason why you missed the plane.
(2) I don’t know the reason why he looks unhappy today.
註意：關系副詞引導的從句可以由“介詞+關系代詞”引導的從句替換
(1) The reason why/ for which he refused the invitation is not clear,
(2) From the year when/in which he was going to school he began to know what he wanted when he grew up.
(3) Great changes have taken place in the city in which./where I was born.
編輯本段（六）判斷關系代詞與關系副詞
方法壹： 用關系代詞，還是關系副詞完全取決於從句中的謂語動詞。不及物動詞後面無賓語，就必須要求用關系副詞或者是介詞加關系代詞；而及物動詞後接賓語，則要求用關系代詞。例如：
This is the mountain village where I stayed last year.
I'll never forget the days when I worked together with you.
判斷改錯（註：先顯示題，再顯示答案，橫線；用不同的顏色表示出。）
（錯） This is the mountain village where I visited last year.
（錯） I will never forget the days when I spent in the countryside.
（對） This is the mountain village (which) I visited last year.
（對） I'll never forget the days (which) I spent in the countryside.
習慣上總把表地點或時間的名詞與關系副詞 where, when聯系在壹起。此兩題錯在關系詞的誤用上。
方法二： 準確判斷先行詞在定語從句中的成分(主、謂、賓、定、狀)，也能正確選擇出關系代詞/關系副詞。例1. Is this museum ___ you visited a few days ago?
A. where B. that C. on which D. the one
例2. Is this the museum ____ the exhibition was held?
A. where B. that C. on which D. the one答案：
例1 D，例2 A
例1變為肯定句： This museum is ___ you visited a few days ago.例2變為肯定句： This is the museum ___ the exhibition was held.
在句1中，所缺部分為賓語，而where, that, on which都不能起到賓語的作用，只有the one既做了主句的表語，又可做從句的賓語，可以省略關系代詞，所以應選D。
而句2中, 主、謂、賓俱全，從句部分為句子的狀語表地點，既可用副詞where，又因 in the museum詞組，可用介詞in + which 引導地點狀語。而此題中，介詞on 用的不對，所以選A。
關系詞的選擇依據在從句中所做的成分，先行詞在從句中做主、定、賓語時，選擇關系代詞 (who, whom, that, which, whose)；
先行詞在從句中做狀語時，應選擇關系副詞 ( where 地點狀語，when 時間狀語，why 原因狀語) 。
編輯本段（七）介詞+關系詞
1）介詞後面的關系詞不能省略。
2）that前不能有介詞。
3） 某些在從句中充當時間，地點或原因狀語的"介詞+關系詞"結構可以同關系副詞when ,where和why 互換。 This is the house in which I lived two years ago.
This is the house where I lived two years ago.
Do you remember the day on which you joined our club?
Do you remember the day when you joined our club?
This is the reason why he came late.
This is the reason for which he came late.
編輯本段（八）先行詞和關系詞二合壹
1)Whoever spits in public will be punished here. (Whoever 可以用 anyone who 代替) 2)The parents will use what they have to send their son to technical school. (what 可以用all that代替)
編輯本段（九）as,which引導的非限定性定語從句
由as, which 引導的非限定性定語從句，as和which可代整個主句，相當於and this或and that。As壹般放在句首，which在句中。
As we know, smoking is harmful to one's health.
The sun heats the earth, which is very important to us.
典型例題
1）Alice received an invitation from her boss, ___came as a surprise.
A. it B. that C. which D. he
答案C. 此為非限定性從句，不能用 that修飾，而用which.，it 和he 都使後句成為句子，兩個獨立的句子不能單以逗號連接。況且選he句意不通。
2）The weather turned out to be very good, ___ was more than we could expect.
A. what B. which C. that D. it
答案B。
which可代替句子，用於非限定性定語從句，而what不可。That 不能用於非限定性定語從句，it不為連詞，使由逗號連接的兩個句子並在壹起在英語語法上行不通。
3）It rained hard yesterday, ____ prevented me from going to the park..
A. that B. which C. as D. it
答案B.
as 和which在引導非限制性定語從句時，這兩個關系代詞都指主句所表達的整個意思，且在定語從句中都可以作主語和賓語。但不同之處主要有兩點：
(1） as 引導的定語從句可置於句首，而which不可。
(2） as 代表前面的整個主句並在從句中作主語時，從句中的謂語必須是系動詞；若為行為動詞，則從句中的關系代詞只能用which.。
在本題中，prevent由於是行為動詞，所以正確選項應為B。
As 的用法例
1. the same… as；such…as 中的as 是壹種固定結構, 和……壹樣……。
I have got into the same trouble as he (has).
例2. as可引導非限制性從句，常帶有'正如'。
As we know, smoking is harmful to one's health.
As is knew, smoking is harmful to one's health.
As是關系代詞。例1中的as作know的賓語；
例2中，它充當從句的主語，謂語動詞know要用被動式。
編輯本段（十）關系代詞that 的用法
(1)不用that的情況
(a) 在引導非限定性定語從句時。
(錯)The tree, that is four hundred years old, Is very famous here.
(b) 介詞後不能用。
We depend on the land from which we get our food.
We depend on the land that/which we get our food from.
(2) 只能用that作為定語從句的關系代詞的情況
(a) 在there be 句型中，只用that，不用which。
(b) 在不定代詞，如：anything, nothing, the one, all, much, few, any, little等作先行詞時，只用that，不用which。
(c) 先行詞有the only, the very,the same,the last,just修飾時，只用that。
(d) 先行詞為序數詞、數詞、形容詞最高級時，只用that。.
(e) 先行詞既有人，又有物時。
(f) 先行詞指物，在主句中作表語時．
(g) 為了避免重復．
(h)先行詞是the way時
舉例：
Is this the book that you borrowed in the library?
這是妳在圖書館借的那本書嗎？
Who that break the window should be punished．
誰打碎了窗戶都要受到懲罰．
All that is needed is a supply of oil.
所需的只是供油問題。
Finally, the thief handed everything that he had stolen to the police.
那賊最終把偷的全部東西交給了警察。
編輯本段（十壹）難點分析
（壹）限制性定語從句只能用that的幾種情況
1．當先行詞是anything, everything, nothing (something 除外), few, all, none, little, some等代詞時，或者是由every, any, all, some, no, little, few, much等修飾時
(1) Have you taken down everything that Mr. Li has said?
(2) There seems to be nothing that seems impossible for him in the world.
(3) All that can be done has been done.
(4) There is little that I can do for you.
註意：當先行詞指人時，偶爾也可以用who
(4) Any man that/.who has a sense of duty won’t do such a thing.
2. 當先行詞被序數詞修飾
(1) The first place that they visited in London was the Big Ben.
3. 當先行詞被形容詞最高級修飾時
(1) This is the best film that I have seen.
4. 當形容詞被the very, the only 修飾時
(1) This is the very good dictionary that I want to buy,
(2) After the fire in his house, the old car is the only thing that he owned.
當先行詞指人時，偶爾也可以用who
(3) Wang Hua is the only person in our school who will attend the meeting？
5. 當先行詞前面有who, which等疑問代詞時
(1) Who is the man that is standing there?
(2) Which is the T-shirt that fits me most?
6. 當先行詞既有人，也有動物或者物體時
(1) Can you remember the scientist and his theory that we have learned?
（二）關系代詞as和which引導的定語從句as和which引導非限制性定語從句，有相同之處也有不同之處。具體情況是：
1．As和which都可以在定語從句中做主語或者賓語，代表前面整個句子。
(1) He married her, as/which was natural.
(2) He was honest, as/which we can see.
2. as 引導非限制性定語從句，可放在主句之前，或者主句之後，甚至可以切割壹個主句；which引導的非限制性定語從句只能放在主句之後。另外，as有“正如……，正像……”的意思
(1) As is known to all, China is a developing country.
(2) He is from the south, as we can see from his accent.
(3) John, as you know, is a famous writer.
(4) He has been to Paris more than several times, which I don’t believe.
註意：當主句和從句存在邏輯上的因果關系時，常用which
(5) Tom was always late for school, which made his teacher angry.
3. 當先行次受such, the same修飾時，常用as
(1) I have never heard such a story as he tells.
(2) He is not such a fool as he looks.
(3) This is the same book as I lost last week.
註意：當先行詞由the same修飾時，偶爾也用that引導定語從句，但是和由as所引導的定語從句意思不同
(4) She wore the same dress that she wore at Mary’s wedding.
她穿著她在MARY婚禮上穿過的壹條裙子。
(5) She wore the same dress as her young sister wore. 她穿著和她妹妹所穿的壹樣的裙子。
(三）以the way為先行詞的定語從句通常由in which, that引導，而且通常可以省略。
(1) The way in which/ that/./ he answered the question was surprising.
(四) but有時也可以做關系詞引導定語從句
(1) There are very few but understand his idea.
( but= who don’t )
(五) 區分定語從句和同位語從句
1．定語從句修飾先行詞，它和先行詞是修飾關系；
同位語從句說明先行詞的具體內容，是補充說明的關系
(1) The plane that has just taken off is for London. 定語從句
(2) The fact that he has been dead is clear. 同位語從句
2．定語從句由關系代詞或者關系副詞引導，關系詞在句中充當成分，有時可以省略；
同位語從句主要由that引導，在句中壹般不做成分；
句子也可以由when, where, how, why, whether, what等詞引導，充當成分
(1) The news he told me is true.
(2) The news that he has just died is true.
(3) The problem that we are facing now is how we can collect so much money. 定語
(4) The problem how we can collect so much money is difficult to solve.
3. 同位語從句和先行詞壹般可以用be動詞發展成壹個完整的句子，而定語從句不可以
(1) The idea that we could ask the teacher for advice is wonderful. 同位語
(2) The idea was that we could ask the teacher for advice.
(3) The fact that the earth moves around the earth is known to all.
(4) The fact is that the earth moves around the earth.
18. 定語從句
定語從句（Attributive Clauses）在句中做定語，修飾壹個名詞或代詞，被修飾的名詞,詞組或代詞即先行詞。定語從句通常出現在先行詞之後，由關系詞（關系代詞或關系副詞）引出。
關系代詞有：who, whom, whose, that, which等。
關系副詞有： when, where, why等。
18.1 關系代詞引導的定語從句
關系代詞所代替的先行詞是人或物的名詞或代詞，並在句中充當主語、賓語、定語等成分。關系代詞在定語從句中作主語時，從句謂語動詞的人稱和數要和先行詞保持壹致。
1）who, whom, that
這些詞代替的先行詞是人的名詞或代詞，在從句中所起作用如下：
Is he the man who/that wants to see you?
他就是妳想見的人嗎？（who/that在從句中作主語）
He is the man whom/ that I saw yesterday.
他就是我昨天見的那個人。（whom/that在從句中作賓語）
2) Whose 用來指人或物，(只用作定語, 若指物，它還可以同of which互換）, 例如：
They rushed over to help the man whose car had broken down. 那人車壞了，大家都跑過去幫忙。
Please pass me the book whose (of which) cover is green. 請遞給我那本綠皮的書。
3）which, that
它們所代替的先行詞是事物的名詞或代詞，在從句中可作主語、賓語等，例如：
A prosperity which / that had never been seen before appears in the countryside. 農村出現了前所未有的繁榮。（which / that在句中作賓語）
The package (which / that) you are carrying is about to come unwrapped. 妳拿的包快散了。(which / that在句中作賓語）
〔定語從句〕介詞+關系詞
1）介詞後面的關系詞不能省略。
2）that前不能有介詞。
3）某些在從句中充當時間，地點或原因狀語的"介詞+關系詞"結構可以同關系副詞when 和where 互換。例如：
This is the house in which I lived two years ago. 這是我兩年前住過的房子。
This is the house where I lived two years ago.
Do you remember the day on which you joined our club？ 還記得妳加入我們俱樂部的那壹天嗎？
Do you remember the day when you joined our club？