luda 概念
定语可以用形容词、名词、代词、分词、不定式、介词短语等形式担任，也可以用一句话来说，或者用定语功能的句子叫做定语从句。
定语从句所修饰的词叫作先行词，引导定语从句的词叫关系词，定语从句放在先行词的后面。定语从句“三要素”
1.先行词：被定语从句所修饰的名词或代词
①指人的先行词②指物的先行词
★ 先行词还可以是前面整个句子所叙述的事情。He has passed the driving test, which surprises all of us. (which替代前面所叙述的事情) 先行词
2.关系词：引导定语的词
(1)关系词的作用
①替代前面的先行词（替代作用）
②连接主句和定语从句（连接作用）
③在定语从句中作句子成分（成分作用）
(2)关系词的分类
①标准：根据关系词在从句中做的句子成分种类
②关系代词：在从句中做 主，宾，表，定（that/which/who/whom/whose/as）
③关系副词：在从句中作状语(When/where/why)引导定语从句的是关系代词that,which,who,whose,whom和关系副词when,where,why。
关系代词或关系副词既起连接作用,又充当从句中的一个成分。关系词作用先行词例句
that,who,whom(只作宾语)主语、宾语、表语 /人
Do you know the old man who/that is standing under the tree?你认识站在树下的那个老人吗?
that,which主语、宾语、表语 /物
She got a computer which/that her parents bought for her.她有一台电脑,这台电脑是她父母买给她的。
whose定语人/物
The boy whose father is a doctor studies very hard.这个男孩学习非常刻苦,他爸爸是位医生。
The room whose window is open is mine.开着窗户的那个房间是我的。
when状语时间
I still remember the day when you left for Beijing.我仍然记得你前往北京的那一天。
where状语地点
This is the school where my mother works.这就是我妈妈工作的那所学校。
why状语原因Could you explain the reason why you were late?你能解释一下你迟到的原因吗?
3.定语从句：用来做定语，修饰限定先行词的句子
定语从句的分类
1.限制性定语从句：对先行词起限定修饰作用。
He is a teacher who works at our school.
2.非限制性定语从句：对先行词起补充说明作用(先行词与定语从句之间有逗号隔开)
Beijing, which is the capital of China, is a beautiful city with a long history.
比较：He has two sons, who work in the same company. (He has only two sons.)
He has two sons who work in the same company. (Perhaps he has two more sons)
限制性定语从句与非限制性定语从句的区别
1. 形式不同 限制性定语从句主句和从句之间不用逗号隔开，口语中使用时也不停顿；而非限制性定语从句与主句之间通常有逗号隔开，口语中使用时有停顿。
2. 功能不同 限制性定语从句用于对先行词的意义进行修饰、限制和识别，如果去掉，就会造成句意不完整或概念不清；而非限制性定语从句用于对先行词起补充说明作用，如果省略，句意仍然清楚、完整。
☛People who take physical exercise live longer. 进行体育锻炼的人活得长些。(若把从句去掉句子就失去意义) ☛His daughter, who is in Boston now, is coming home next week. 他女儿现在在波士顿，下星期回来。(若把从句去掉，句子意义仍然完整)
3. 翻译不同 在翻译定语从句时，一般把限制性定语从句翻译在它所修饰的先行词之前，而把非限制性定语从句与主句分开。
☛He is the man whose car was stolen. 他就是汽车被窃的那个人。
☛I’ve invited Jim, who lives in the next flat. 我邀请了吉姆，他就住在隔壁。
4. 含义不同比较下面的两个句子： ☛I have a sister who is a doctor. 我有一个医生的姐姐。(姐姐不止一个)
☛I have a sister, who is a doctor. 我有一个姐姐，她是当医生的。(只有一个姐姐)
5. 先行词不同 限制性定语从句的先行词只能是名词或代词，而非限制性定语从句的先行词则可以是名词或代词，也可以是短语或句子；另外，当先行词为专有名词或其他具有独一无二性的普通名词时，通常要用非限制性定语从句，而不用限制性定语从句。
☛Peter drove too fast, which was dangerous. 彼得开车很快，这是很危险的。(which指drive too fast)
☛He changed his mind, which made me very angry. 他改变了主意，这使我很生气。(which指整个主句)
☛Mr. Smith, who is our boss, will leave for Japan next week. 我们的老板史密斯先生下周要去日本。(先行词为专有名词，要用非限制性定语从句修饰)
☛Her father, who has a lot of money, wishes her to study abroad. 她父亲很有钱，希望她出国学习。(先行词为表独一无二意义的普通名词，要用非限制性定语从句修饰)
6. 关系词不同 关系词that和why可用于限制性定语从句中，通常不用于非限制性定语从句；另外，在限制性定语从句中，关系词有时可以省略，而在非限制性定语从句中关系词一律不能省略。
定语从句的10个难点
1.关系代词的省略(限定性定语从句)
(1)关系代词在定语从句中作宾语She is the girl (whom / that) I loved before. (可以省略whom/that)
(2)关系代词在定语从句中作表语He is no longer the boy (that) he used to be. (可以省略that)
(3)关系代词作介词宾语，介词在从句句尾时可以省略Housing price is a problem (that/which) people are interested in.
比较：Housing price is a problem in which people are interested.（此时只能用which且不能省略）
2.先行词是人(that/who的区别)
(1)用that的情况
①以疑问词who开头的句子中
Who is the man that is shouting there?
②关系代词在从句中作表语时
She is not the girl that she used to be.
③先行词被the very, the right, the only修饰
This is the very person that we are looking for.
(2)用who的情况
①先行词是one, ones, anybody, all, none, those 等Those who want to go to the cinema will have to wait at the gate of the school.
②句子中有两个定语从句,一个用了that,另外一个用who
Who is the boy that won the gold medal?
③在there be 结构中
There are many young men who are against him.
④在非限定性定语从句当中
Tom, who is my best friend, has gone abroad to study.
3.先行词是物(that / which的区别)
(1)用which的情况
①在非限定性定语从句中
She lost the game, which depressed her greatly.
②关系词置于介词之后，作宾语
The pen with which you write is Jack’s.
③先行词是that或定语从句中套定语从句,一个关系词用that,另一个用which.
Let me show you the novel that I borrowed from the library which is newly open to us.
(2)关系词只用that的情况
①先行词是不定代词如all, little, few, much,anything, everything, nothing, none, no one等
She did all that she could to help us.
②先行词被all, every, no, some, little, much, the only, he very, the right，the last等所修饰时
This is the very book that I want.
③先行词中既有人又有物时
She described in her compositions the people and he places that impressed her most.
④先行词前有序数词或形容词最高级修饰时
This is the best book that I have ever read.This is the first film that I’ve seen since I came here.
⑤定语从句中套定语从句，其中一个关系词以用which, 另外一个用that
He built a factory which produced things that had never been seen before.
⑥当主句的主语是疑问词which,另一个用that
Who is the person that is standing at the gate?
关系词只能用which的几种情况: ①关系代词放在介词之后。如： This is the factory in which we once worked. 这就是我们曾经工作过的工厂。
②非限制性定语从句中。如： This is a famous book, which was written by Lu Xun. 这是鲁迅写的一本有名的书。
③that， those作主语时。如： Those which are on the desk are English books. 桌子上的那些是英语书。
用who而不用that的情况:
①当先行词为people和those时，只能用who。
如： Those who want to go there come here please. 那些想去那儿的人请来这边。
②当先行词为one, ones, anyone, everyone, none, all(指人)时，只能用who。如：Anyone who is against us is our enemy. 任何反对我们的人就是我们的敌人。
③先行词指人，而关系代词在从句中作主语时，一般多用who。如： The man who came here yesterday said he would come again in a few days. 昨天来这儿的那个人说过几天他会再来。
4.As引导定语从句用法
(1)As 既可以引导限制性定语从句也可以用于非限定性定句中充当主语，宾语，表语等。
常用于以下句型当中：Such/so….. as…. 像…..一样 the same …. as… 和…...同样的A computer is so useful a machine as we can use everyday.He is not the same man as he was.
(2)引导非限制性定语从句，此时译为“正如，像”等。可以放在句首，句中或句末。
As I remember, there were a net bar is an inseparable part of China, as is known to all.
★the same as...和the same that...引导定语从句的区别This is the same bike that I lost yesterday. (同一事物)This is the same bike as I lost yesterday. （同类事物）
5.关系副词的运用
(1)When 在定语从句中做时间状语，先行词为表示时间的time, day等
I still remember the day when I first came to Beijing. (when=on which)
(2)Where 在定语从句中做地点状语，先行词为表地点的place, spot等
Can you tell me the office where he works? (where = in which)
(3)Why 在定语从句中做原因状语，先行词只有reason.
I don’t want to listen to any reason why you were absent. (why = for which)
★ 关系副词 = 相应的介词 + 关系代词
★ Where引导的定语从句还可以修饰抽象空间的名词如case(情形)，situation, position(位置),stage (阶段)，point（地步）等
What are the situations where body language is the only form of communication?在哪些情况下身体语言是唯一的沟通方式。(此时where = in which)
6.几个特殊的先行词
(1)way在定语从句中做状语时的三种引导方式 that / in which / 不填The way in which / that / 不填
he explains the sentence to us is quite simple.
比较：The way which /that/不填 he told to us was quite simple.
★way在定语中作tell的宾语
(2)先行词time
time表示“次数”时，用关系代词that引导定语从句
This is the first time that the president has visited the country.
time作“一段时间” 讲时，应用关系副词whenThis was the time when there were no radios, no telephones or no TV sets
★此时when = during which 在..期间
(3)先行词reason当在定语从句中作状语时，定语从句的4种引导方式 why/for which/that/不填This is the reason why/for which/that/不填
he can not come here.
比较：Is this the reason that/which/不填he explained to us for his absence from the conference.
★reason 在定语从句中做explain的宾语
7.介词+关系代词
★该结构的关系代词只有两种即 介词+which（指物） 介词+whom（指人）
★该结构介词的选用原则：
(1)根据定语从句中谓语动词的习惯搭配
This is the book on which I spent $ 8.This is the book for which I paid $ 8.
(2)根据先行词的搭配习惯
I remember the days during which I lived remember the day on which I graduated from university.
(3)根据整个句子所表达的意思来决定The colorless gas without which we can’t live is called oxygen.
(4)英语中为了强调某一名词，不定式前面也可以加上关系代词。Here is the money with which to buy the is the right person on whom to depend
注意：
①如果介词后移，关系代词可以省略The person (whom/who/that) you will write to is Todd.
②有些含有介词的动词短语介词不能提前如look for/after; take care of; send for; hear from/of/about deal with等This is the baby that you will look after.
8.定语从句的主谓一致
(1)当先行词是 one of + 复数名词，定语从句的位于动词要用复数形式The Great Wall is one of the world-famous buildings that draw lots of visitor every year.(
2)当先行词是 the only + one of +复数名词，从句谓语用单数形式The Great Wall is the only one of the buildings on the earth that is seen from the moon.
(3)先行词如果是整个句子，定语从句的谓语动词用单数Great changes have taken place in China, as is known to all.He has passed the driving test, which surprises all of us.
9.定语从句的转化
定语从句可以转换为 –ing或-ed形式
The girl (who is) dancing now just returned from Taiwan.I love the stories (which were) written by Hemingway.The man (who stands) standing there is my friend.
10. 定语从句的解题方法
(1)判断从句是否为定语从句 （先行词，关系词，定语从句）(2)准确判断先行词在定语从句中的成分(主、宾、表、定、状)从而正确选定使用关系代词或关系副词
注意：
①关系代词whose的用法。Whose在定语从句中做定语。当先行词是人：whose = the + 名词 + of whom 当先行词是物：whose = the + 名词 + of whichDo you know the boy whose parents / the parents of whom are on holiday?I’d like a room whose window / the window of which faces the sea.
②That引导定语从句，名词性从句 和 强调句型的区别:定语从句中的that: 关系代词，在后面的定语从句中做句子成分。名词性从句中的that：从属连词，只起连接主从句的作用，在从句中不做句子成分。强调句中的that, 运用于it is/was…that..结构；判断标准：去掉强调句型结构，成分仍然完整。
比较：This is the book that I am looking for. (that 引导定语从句)
It is at Bashu middle school that I have studied for three years. (that和前面的it is构成强调句型)
The fact that he stole the money surprised all of us.(that 引导名词性从句--同位语从句)
That he will come to the conference has excited all of us.(that引导名词性从句--主语从句)
We all expect that they win, for members of their team are stronger.(that引导名词性从句--宾语从句)
The reason for your failure is that you lack confidence in yourself.(that 引导名词性从句--表语从句)
定语从句与同位语从句的区别
定语从句与同位语从句的区别：
1. 被修饰的词不同：同位语从句的前面一般是数量有限的、表示抽象意义的名词；而定语从句的先行词是无数的指人或物名词。
2. 从句的作用不同：同位语从句表示同位名词的具体内容，而定语从句是对先行词的限制、描绘或说明。
3. 引导词不同：what, how, whether等不能用引导定语从句，但可用于引导同位从句。
4. 引导词的作用不同：引导同位语从句的that是连词，在从句中不充当任何成分；而引导定语从句的that为关系代词，在从句中充当一定的句子成分。
5. 判定定语从句和同位语从句的方法：由于同位语从句是用以说明被修饰名词的具体内容的，所它可以转换同位名词的表语；而定语从句则不能作这种转换。
定语从句与强调句型的区别
定语从句对名词或代词的修饰和限制，关系词可能是that, which, as, who, but, 另一方面，句子中的It有所指；而强调句型是对某部分加强语气，强调语气的连接词只能是that, who，并且句子中的It 没有任何意义；一般比较明显，而有时就难以区别，还需要根据上下文的语境来判断。它究竟是强调句型还是定语从句，就要从语境上来考查。如果它是用来回答What is this / that? 这样的问题，意思是：它是一本他想要的书。句子显然是定语从句。如果是用来回答What does he want? 这样的问题，那么意思是：他想要的是一本书。显然，句子是强调句型。
关系代词as和which的区别关系代词as和which引导定语从句的不同点
1. as可以放在主句前后，也可插入主句之中；而which引导的非限制性定语从句只能位于主句之后。
2. 在非限制性定语从句中，which后的be动词不可省；而as后的be动词可以省略。
3. which在非限制性定语从句中作主语时可用各类动词作谓语；而as作主语时，谓语常用系动词，如be，seem，become等，一般不用其他行为动词。
4. as常用＂正如＂含义，常用的结构有as we know（众所周知）；as often happens（正如常发生的那样）；as is often the case（情况常常如此）；as we all can see（正如我们看到的）；be announced / expected / known / imagined / mentioned / said / shown / reported等。这些结构常放句首，偶尔也可以放句中或句末。
5. 非限制性定语从句中，which可指代主句中的某一个单词，as不可以。
6. ＂介词+关系代词（介宾代物）＂中关系代词只能用which。7. 从句中的谓语动词是否定形式时，常用which。