英语语法要点大全： 定语从句
英语语法要点大全： 定语从句
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定语从句在句中做定语，修饰一个名词或代词，被修饰的名词,词组或代词即先行词。定语从句一般出目前先行词之后，由关系词引出。
关系代词有：who, whom, whose, that, which等。
关系副词有：when, where, why等。
18.1 关系代词引导的定语从句
关系代词所代替的先行词是人或物的名词或代词，并在句中充当主语、宾语、定语等成分。关系代词在定语从句中作主语时，从句谓语动词的人称和数要和先行词维持一致。
1)who, whom, that
这类词代替的先行词是人的名词或代词，在从句中所起用途如下：
Is he the man who/that wants to see you?
他就是想见你的人吗?
He is the man whom/ that I saw yesterday.
他就是我昨天见的那个人。
2) Whose 用来指人或物，, 比如：
They rushed over to help the man whose car had broken down. 那人车坏了，大伙都跑过去帮忙。
Please pass me the book whose cover is green. 请递给我那本绿皮的书。
3)which, that
它们所代替的先行词是事物的名词或代词，在从句中可作主语、宾语等，比如：
A prosperity which / that had never been seen before appears in the countryside. 农村出现了前所未有些兴盛。
The package you are carrying is about to come unwrapped. 你拿的包快散了。
18.2 关系副词引导的定语从句
关系副词可代替的先行词是时间、地址或理由的名词，在从句中作状语。
1)when, where, why
关系副词when, where, why的意思等于介词+ which结构，因此常常和介词+ which结构交替用，比如：
There are occasions when one must yield. 其他人都有不能不屈服的时候。
Beijing is the place where I was born. 北京是我的出生地。
Is this the reason why he refused our offer? 这就是他拒绝大家帮助他的原因吗?
2)that代替关系副词
that可以用于表示时间、地址、方法、理由的名词后取代when, where, why和介词+ which引导的定语从句，在口语中that常被省略，比如：
His father died the year he was born. 他爸爸在他出生那年去世了。
He is unlikely to find the place he lived forty years ago. 他不大可能找到他四十年前居住过的地方。
18.3 判断关系代词与关系副词
办法1、 用关系代词，还是关系副词完全取决于从句中的谓语动词。及物动词后面无宾语，就需要需要用关系代词;而不及物动词则需要用关系副词。比如：
This is the mountain village where I stayed last year.
Ill never forget the days when I worked together with you.
判断改错
This is the mountain village where I visited last year.
I will never forget the days when I spent in the countryside.
This is the mountain village I visited last year.
Ill never forget the days I spent in the countryside.
习惯上总把表地址或时间的名词与关系副词 where, when联系在一块。此两题错在关系词的误用上。
办法2、 准确判断先行词在定语从句中的成分，也能正确选择出关系代词/关系副词。
例1. Is this museum ___ you visited a few days age?
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变为一定句： This museum is ___ you visited a few days ago.
例2变为一定句： This is the museum ___ the exhibition was held.
在句1中，所缺部分为宾语，而where, that, on which都不可以起到宾语有哪些用途，只有the one既做了主句的表语，又可做从句的宾语，可以省略关系代词，所以应选D。
而句2中, 主、谓、宾俱全，从句部分为句子的状语表地址，既可用副词where，又因 in the museum词组，可用介词in + which 引导地址状语。而此题中，介词on 用的不对，所以选A。
关系词的选择依据在从句中所做的成分，先行词在从句中做主、定、宾语时，选择关系代词 ; 先行词在从句中做状语时，应选择关系副词 。
18.4 限制性和非限制性定语从句
1) 定语从句有限制性和非限制性两种。限制性定语从句是先行词不可或缺的部分，去掉它主句意思总是不清楚;非限制性定语从句是先行词的附加说明，去掉了也不会干扰主句的意思，它与主句之间一般用逗号分开，比如：
This is the house which we bought last month. 这是大家上个月买的那幢房屋。
The house, which we bought last month, is very nice.这幢房屋非常漂亮，是大家上个月买的。
2) 当先行词是专有名词或物主代词和指示代词所修饰时，其后的定语从句一般是非限制性的，比如：
Charles Smith, who was my former teacher, retired last year. 查理史密斯去年退休了，他过去是我的老师。
My house, which I bought last year, has got a lovely garden. 我去年买的的那幢房屋携带个好看的花园。
This novel, which I have read three times, is very touching. 这本小说非常动人，我已经读了三遍。
3) 非限制性定语从句还能将整个主句作为先行词, 对其进行修饰, 这个时候从句谓语动词要用第三人称单数，比如：
He seems not to have grasped what I meant, which greatly upsets me. 他好像没抓住我的意思，这使我心烦。
Liquid water changes to vapor, which is called evaporation. 液态水变为蒸汽，这就叫做蒸发。
说明：关系代词that和关系副词why不可以引导非限制性定语从句。
18.5 介词+关系词
1)介词后面的关系词不可以省略。
2)that前不可以有介词。
3) 某些在从句中充当时间，地址或缘由状语的介词+关系词结构可以同关系副词when 和where 互换。
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?
18.6 as, which 非限定性定语从句
由as, which 引导的非限定性定语从句，as和which可代整个主句，等于and this或and that。As通常放在句首，which在句中。
As we know, smoking is harmful to ones health.
The sun heats the earth, which is very important to us.
典型例题
1)Alice received an invitation from her boss, ___came as a surprise.
A. it B. that C. which D. he
答案C. 此为非限定性从句，不可以用 that修饰，而用which.，it 和he 都使后句成为句子，两个独立的句子不可以单以逗号连接。况且选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，用于非限定性定语从句，而what不可。That 不可以用于非限定性定语从句，it不为连词，使由逗号连接的两个句子并在一块在英语语法上行不通。
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在引导非限制性定语从句时，这两个关系代词都指主句所表达的整个意思，且在定语从句中都可以作主语和宾语。但区别主要有两点：
as 引导的定语从句可置于句首，而which不可。
as 代表前面的整个主句并在从句中作主语时，从句中的谓语需要是系动词;若为行为动词，则从句中的关系代词只可以用which.。
在本题中，prevent因为是行为动词，所以正确选项应为B。
As 的使用方法
例1. the same as;suchas 中的as 是一种固定结构, 和一样。
I have got into the same trouble as he .
例2. as可引导非限制性从句，常带有正如。
As we know, smoking is harmful to ones health.
As is know, smoking is harmful to ones health.
As是关系代词。例1中的as作know的宾语;例2中，它充当从句的主语，谓语动词know要用被动式。
18.7 先行词和关系词二合一
1)Whoever spits in public will be punished here.
2)The parents will use what they have to send their son to technical school.
18.8 what/whatever;that/what; who/whoever
1)what = the thing which;whatever = anything
What you want has been sent here.
Whatever you want makes no difference to me.
2) who= the person that whoever= anyone who
Who breaks the law will be punished.
Whoever robbed the bank is not clear.
Whoever breaks the law will be punished.
Who robbed the bank is not clear.
3) that 和 what
当that引导定语从句时 ，一般用作关系代词，而引导名词性从句时，是个不充当任何成分的连接词。宾语从句和表语从句中的that常可省略。What只能引导名词性从 句， 用作连接代词，作从句的具体成分，且不可以省略。
I think you will like the stamps.
What we need is more practice.
18.9 关系代词that 的使用方法
1)不需要that的状况
a) 在引导非限定性定语从句时。
The tree, that is four hundred years old, is very famous here.
b) 介词后不可以用。
We depend on the land from which we get our food.
We depend on the land that/which we get our food from.
2) 只可以用that作为定语从句的关系代词的状况
a) 在there be 句型中，只用that，不需要which。
b) 在不定代词，如：anything, nothing, the one, all, much, few, any, little等作先行词时，只用that，不需要which。
c) 先行词有the only, the very修饰时，只用that。
d) 先行词为序数词、数词、形容词最高级时，只用that。.
e) 先行词既有人，又有物时。
举例：
All that is needed is a supply of oil.
所需的只不过供油问题。
Finally, the thief handed everything that he had stolen to the police.
那贼最后把偷的全部东西交给了警察。
