初三英语语法------定语从句
一、定语从句的有关概念：
在复合句中，修饰某一名词或代词的从句叫做定语从句。
如：1)The man who/that lives next to us is a policeman.
2)You must do everything that I do.
在上面两句中的 man 和everything 是定语从句所修饰的词，叫先行词。定语从句放在先行词后面。
引导定语从句的关系词有关系代词：that , which ,who (宾格whom ,所有格whose )和关系副词where, when .关系词（关系代词或关系副词）放在先行词和定语从句之间，起联系作用，同时又作定语从句的一个成分。也就是说关系词有两个作用：
1.引导定语从句。
2.代替先行词在其引导的定语从句中充当一定的句子成分。
二、有关系代词引导的定语从句：
关系代词 例句
That在从句中作主语或宾语(作宾语时that 可省略) 指物 1.A plane is a machine that can fly. (作主语)
2.The noodles （that） I cooked were delicious. (作宾语)
指人 1.Who is the man that is reading the book over there? (作主语)
2.The girl (that) we say yesterday was Jim’s sister. (作宾语)
Which在从句中作主语或宾语(作宾语时可省略)
指物
1.The silk which is produced in Hangzhou sells well. (作主语)
2.The songs （which） Liu Dehua sang were very popular. (作宾语)
Who, whom在从句中分别作主语和宾语（如果介词放在从句后面，则whom可以省略）
指人 1.The foreiger who visited our class yesterday is from Canada. (作主语)
2.The boy who break the window is called Roy. (作主语)
3.The person to whom you just talked is Mr Li. (作宾语)
4.Mrs White is the person to whom you should write. (作宾语)
Whose 在从句中作定语 指人或物的所有格 I like the girl whose hair is long. (作定语)


（从表中可以看出：用that 更有通用性）
三、有关系副词引导的定语从句：(只作了解)
1. 1. 先行词是表示地点的名词时（country, school, room…），而关系词代替先行词在定语从句中充当地点状语，一般用where引导定语从句。也可以用介词＋which的结构。值得注意的是which前介词的选择是根据先行词与介词的搭配关系而定。
　　The room where(=in which)he used to live has now been turned into a museum..　　The desk where(=on which)I put my bag is his.
This is the school where(=in which)I joined the Party.
2. 2. 先行词是表示时间的名词（year,month,day,night…），而关系词代替先行词在定语从句中充当时间状语，一般用when引导定语从句。也可以用介词＋which的结构。值得注意的是which前介词的选择是根据先行词与介词的搭配关系而定。
The day when（=on which）he was born was　Aug.20,1952
The year when (=in which) he died was 1982..
四、定语从句分类(只要了解)
定语从句分为：限制性定语从句和非限制性定语从句（又称描述性定语从句）。
1、 限制性定语从句与先行词关系密确，对它有限制作用，因些不可缺少，否则会影响全句的意思，限制性定语从句前面一般不用逗号。
例What is the name of the boy who brought us the letter?
2、非限制性定语从句只与先行词有一种松散的修饰关系，在口语中用停顿的方法表示，
在书面语中用逗号分开，因此从句中的关系代词不能省略。一般用which ,who, where等来引导非限制性定语从句，而不用that 来引导非限制性定语从句。
例① 例①I like talk with John, who is a clever man.
例② 例②Water ,which is a clear liquid (液体)，has many uses.
五、关于that ;which 用法请注意：
①先行词之前有all, every, any, no ,little, much, few 等词修饰时，或者其本身为all, everyone, everybody, everything, nobody, nothing, anything ,anyone ,anybody等不定代词，代替物时，定语从句that用引导。　　
注：something后一般用which。
　　Is there anything that you want to explain ?
　　Everyone that heard her sad story was moved to tears.
In 1898 they declared（声明） that they believed there was something in nature which gave out radiation.(辐射)
②先行词前有形容词最高级、序数词或only, very, none, the first, the last, the same表示“惟一”观念的形容词等修饰时，定语从句用that引导。That 可指人，也可指物。
This is the only reason that I can say.
This is the first step that can be taken.
It is the best one that you may choose.
③ 当主句中有who/which时，而定语从句中也要用到who或which时，为了避免who…who, which…which等重叠，定语从句用that引导。
　 　Who is the man that is standing by the door?
Which of the two cows that you keep produces more milk?
④先行词为人和物作并列成分时，定语从句用that引导。
　　John and his dog that were here a moment ago disappear now.
⑤不论人或物在定语从句中作表语时，用that引导定语从句，而that通常省掉。
　　 He is no longer the man that he was.
⑥先行词是一个短语或者是一个句子时，关系代词用 which (大多数情况是非限制性定语从句)
He missed the train ,which annoyed (使。。。恼火) him very much .
五、注意事项：
1. 1. 一般说来，除了用定语从句解释名词或泛指外，先行词前应有定冠词the。
2. 2. 在限制性定语从句中which, whom, that充当宾语时，可以省略。而在非限制性定语从句中whom, who, which不能省略。
3. 3. 在含有非限制性定语从句的复合句中从句与主句之间应该用逗号隔开。
　　4.“one of＋可数名词复数”引导的定语从句中,谓语动词应用复数；而“one of＋可数名词复数”前有the，only或the only修饰，定语从句中的谓语动词用单数。
He is one of the students who study very hard at school.
He is the(only/the only) one of the students who studies very hard at school.