【名师点拨】
本专题主要讲解了定语从句的一些基本特点及用法，包括关系代词及关系副词，以及定语从句的分类等，另外也简单讲解了常见关系词的用法，比如高考中常考的that/which/as/who/whom/ whose/when/where/why.等，因此学习的重点是掌握常见关系词的用法。
一、定语从句的定义
定语可以由形容词，名词，代词，数词，分词，副词，不定式及介词短语，句子来担任。担任定语的句子称为定语从句（形容词性从句），作用相当于形容词,用来修辞名词，代词或者整个句子。而这些名词，代词或句子称为先行词。
引导词（关系词:引导定语从句；代替先行词；在定语从句中担当一个成分）： 关系代词: that, which,as,who,whom,whose. 关系副词: when, where, why.
结构：先行词+关系词引导的定语从句 二、定语从句的分类 1. 限制性定语从句
先行词在意义上为不可缺少的定语，如果去掉，主句的意思就不完整或失去意义。这种从句和主句关系十分密切， 写时不用逗号分开。
I was the only person who was invited in my office. 我是唯一一个被邀请到他办公室的人 2. 非限制性定语从句
和主句关系不很密切，只是对先行词作些附加说明，如果去掉，主句的意思仍然清楚。这种从句， 写时往往逗号分开。
Jenny, with whom I played table tennis yesterday, lives in my next room. 昨天和我打乒乓球的詹妮，住在我的隔壁房间里。 三、常见关系代词的基本用法 1. that
可指人或物；在定语从句中作主语，宾语，表语。指人时，相当于who或 whom；指物时，相当于which。一般不用于非限制性定语从句; 不可置于介词后作宾语。如：
（1）A letter that/which is written in pencil is difficult to read. (主语) 用铅笔写的信很难读。
Do you know the gentleman that/who spoke just now? 你认识刚才说话的那位先生吗？
（2） You can take anything ( that) you like. （宾语） 你可以带走任何你喜欢的东西。
What is the question (that/which) they are talking about? 他们刚才讨论的问题的是什么？
Here is the man ( who/whom/that ) you want to see. 你想见的人就在这里。
（3）She's no longer the girl ( that) she used to be before.（表语） 她不再是以前的那个女孩了。
Our hometown is no longer the one (that) it used to be.
我们的家乡已不再是过去的那个了。（= Our hometown is not the same as it used to be.= Our hometown is different from what it used to be。= Our hometown is not what it used to be.）
2. which
指物；在定语从句中作主语，宾语。如：
（1）The book which/that was on the desk was bought by my father.（主语） 书桌上的那本书是我爸爸买的。
（2）The book (which/that) I bought yesterday is very interesting.（宾语） 我昨天买的那本书很有趣。 3. who, whom, whose
（1）who: 主格, 在从句中作主语，只可指人 （2）whom: 宾格，在从句中只能作宾语; 只可指人
（3）whose: 表所属关系，在从句中作定语。译为：某人的，某物的
（4）whose + 名词 =the + n. + of which (某物的) = he + n. + of whom (某人的) 【例句】
（1）I like the students who/that study hard. （主语） 我喜欢学习努力的学生。
The boy (that/ who / whom ) we saw yesterday is Tom. 我们昨天看到的男孩是汤姆。
（2）A child whose parents are dead is called an orphan.（指人） 父母去世了的孩子叫做孤儿。(whose parents = the parents of whom) （3）I'd like a room whose window faces south. （指物）
我喜欢窗户朝南的房间。 注意：
① 关系代词作介词宾语 (在定语从句中，介词提前时，介词后：表人用 whom；表物用 which)
② 关系代词在定语从句中用作介词宾语时, 介词可放于从句之首, 也可放于从句之末. 但以放于句首较为正式（介词前置，.必须注意不影响动词词组的含义。关系代词who 和 that 用作介词宾语时, 介词必须放在句末。）
【例句】
The man (whom / who / that ) my mother is talking with is Mr Black.
正在和我妈妈谈话的男人是布莱克先生。（= The man with whom my mother is talking is Mr Black.）
This is the book for which you asked.
这就是你要找的那本书。（=This is the book (that/which) you asked for.） Do you know the person with whom I shook hands？
你认识和我握手的那个人吗？（= Do you know the person (whom/who/that) I shook hands with?）
The library from which we can borrow books is very big. 我们可以借书的图书馆很大。 4. as
as 引导定语从句, 在定语从句中作主语、宾语、表语)
（1）如为限制性的，多用于the same …as ; the same as(与……相同)；such …as …（如此，这样）; as many/much as（和……一样多）；so/as …as（与……一样）等结构中。如：
I have the same book as you (have). 我有一本和你的一样的书。
Her attitude to him was quite the same as it had always been.
她对他的态度和以前一样。 (关系代词as和指示代词same连用, 在从句中用作表语, 先行词是same.)
---Why didn't you mention that in face of the police just now?
--- I thought it was such a minor detail as was hardly worth mentioning. ---你刚才为什么不在警察面前提起那件事呢？ ---我认为这是一个微不足道的细节，不值一提。
We will only discuss such problems as have something to do with our own interests.
我们只会讨论与自己利益有关的问题。
比较：I live in the same house that he used to live in. 我住在他以前住过的那所房子里。 I'm wearing the same shirt as you wore yesterday. 我穿的衬衫和你昨天穿的一样。 比较：Here is so big a stone as no one can lift. （定语从句） Here is so big a stone that no one can lift it.（结果状语从句）
（2）如为非限制性的，as还可以单独引导一个定语从句，代替整个主句，这种定语从句可置于句首，句中或句尾，译为\正如，这一点\。（动词常为know, see, expect, point out, etc.）
As we all know, smoking is harmful to one's health . (as 作宾语) 众所周知，吸烟有害健康。
=As is known to all, smoking is harmful to one's health .（as 作主语） =It's known to all that smoking is harmful to one's health .
=Smoking is harmful to one's health , as we all know.（as 作宾语） =Smoking, as we all know, is harmful to one' health. He was a foreigner, as I knew from his accent.
我从他的口音知道，他是外国人。(宾语, 先行词是前面整个句子) 众所周知：As we all know,
As is well-know (to us all) It’s well-know (to us all) that… What is well-know is that… 5. when, where, why
关系副词(when, where, why)引导的定语从句,它们后面的句子完整，只缺状语，它们都可以等于介词+ which , 其中 why 只等于 for which。
（1）When 指时间，在定语从句中作时间状语。其先行词是表时间的名词（如：time, day, week, tear, month, etc.）
We will put off the picnic until next week, when the weather would be better. 我们将把野餐推迟到下周，那时天气会好一些。
注意：先行词为\时间名词\，可用when引导定语从句，when在定语从句中作状语；还可以用which或that 引导，which或that在从句中作主语或宾语。
比较: I still remember the day when /on which my brother joined the army.（作状语） 我还记得我哥哥参军那天。
I still remember the days which/that we spent together. （作V.谓语 spent 的宾语） 我仍然记得我们一起度过的日子。
Next winter which/that you'll spend in Harbin, will be exciting.（宾语） 你将在哈尔滨度过下一个冬天，将是令人兴奋的。 There are occasions when joking is not permissible. 有些场合不允许开玩笑。
（2）Where 指地点，在定语从句中作地点状语。其先行词是表示地点的名词，如：place, school, factory, room, etc.
This is the place where I was born. 这里是我出生的地方。
I live in the room where /in which he used to live. 我住在他曾住过的那个房间里。 注意：先行词是\地点名词\，定语从句可用where引导，还可用which或that引导，which/that 在从句中作主语或宾语。比较:
This is the factory where /in which he worked last year. （作状语） 这就是他去年工作的那家工厂。
This is the park which/that they visited last year. （作宾语） 这是他们去年参观过的公园。
（3）Why 指原因，在定语从句中作原因状语。先行词为reason 时，可用for which指代；当关系词在从句中作主语或宾语时，则用which或that 引导。如：
The reason why + 定语从句 is that + 表语从句 （……的原因是……） I don't believe the reason (that/which) he gave me. 我不相信他给我的理由。（作宾语）
He asked me the reason that can explain my success. 他问我能解释我成功的原因。（作主语） (That’s because + 原因) 那是因为……
He got up late. That's why he was late.(表语从句) （That’s why + 结果） 那是……的原因
(the reason) why/for which he was late. (定语从句)
★ 注：当先行词为way时，定语从句常用that, in which,或省略引导词。
way后的定语从句的引导词不用时较多。但如果关系词在句中作主语或宾语时，则用which或that 引导。比较:
This is the way (that) /（in which）I do such things. 这就是我做这些事情的方式。 Please do the experiment in the way（that/which）I have shown you. 请以我向你展示的方式做这个实验。
【小试牛刀】
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