定 语 从 句一、定义及特点：在复合句中用来修饰某一名词或代词的从句叫定语从句其特点是定语从句的引导词是先行词的替身，既起联系作用，同时又充当定语从句的一个成分，所以掌握定语从句的关键在于：弄清楚其先行词的所指、所作成分和可否省略 二、分类及区别：定语从句分为限制性定语从句和非限制性定语从句两种它们的区别有四点：1、从重要性上看：限制性定语从句在整个句子中比拟重要，省去后会影响整个句子意思的表达；而非限制性定语从句那么反之 2、从句子形式上看：限制性定语从句的引导词前面无逗号，而非限制性定语从句的引导词前面有逗号 3、从引导词上看：that，why可以引导限制性定语从句，但却不可以引导非限制性定语从句 4、从引导词可否省略上看：在限制性定语从句中作宾语的引导词可以省略，而在非限制性定语从句中的引导词无论作什么成分都不可以省略 三、用法〔详解〕名称所指所作成分可否省略关系代词that人/物主语/宾语作宾语可省which物主语/宾语作宾语可省who人主语/宾语不能省略whom人宾语不能省略whose人定语不能省略as物主语/宾语/表语/定语/状语不能省略关系副词when时间时间状语不能省略where地点地点状语不能省略why原因原因状语不能省略一、限制性定语从句的用法：〔一〕关系代词引导的定语从句。
1、关系代词that，which，who，whom，whose，as引导的定语从句的用法 ⑴that可以指人，也可以指事物，在定语从句中作主语或宾语〔作宾语时可以省略〕如：Who is the man that is reading a newspaper there？〔作主语指人〕The girl〔that〕we saw yesterday is Jim's sister.〔作宾语指事物〕A dolphin is an animal that lives in the sea.〔作主语指事物〕The moon cakes that mother cooked taste nice.〔作宾语指事物〕 ⑵which指事物，在定语从句中作主语或宾语〔作宾语时可以省略〕如：The silk which is produced in Suzhou sells well.〔作主语指事物〕The song〔which〕the singer sang were very popular.〔作宾语指事物〕⑶who，whom指人：who，whom在定语从句中分别作主语或宾语〔who也可以作宾语，who/whom作宾语时可以省略〕；whose可以指人〔= of whom〕或事物〔=of which〕不可以省略〕。
如：The student who sits on my left is an American.〔作主语指人〕 The person〔who/whom〕you just talked to is our headmaster.〔作宾语指人〕I know the woman whose daughter studies abroad.〔作定语指人〕⑷as指物，常用于such…as，the same…as，as…as结构中，在定语从句中作宾语、表语、定语和状语，不可以省略如：This is not such a book as I expected.〔作宾语指物〕 It is the same place as it used to be.〔作表语指物〕 I like the same book as you do.〔作定语指物〕I shall do it in the same way as you did.〔作状语指物〕〔二〕关系副词引导的定语从句1、关系副词when，where，why引导的限制性定语从句的用法⑴when指时间，在定语从句中作时间状语，不可以省略如：We still remember the years when/during which we studied together.⑵where指地点，在定语从句中作地点状语，不可以省略。
如：This is the place where/in which he lives. ⑶why指原因，在定语从句中作原因状语，不可以省略如：Do you know the reason why/for which I was late for class？定语从句考点讲解根据定语从句先行词的所指〔指人/物/时间/地点/原因〕、先行词的所做成分、及其可否省略，三个因素来综合确定定语从句的引导词一、 四个引导词1.只用that引导定语从句的情况：①领先行词既有人又有物时，只能用that如：They talked about the things and persons that they remembered in the school.②领先行词是数词或all，much，little, everything，anything，nothing，none，the one等指物的不定代词时，只能用that如：Yesterday I caught two fish and put them in a basin of water. Now you can see the two that are still alive. I had to remember everything that the teacher taught me.注意：领先行词是something时，关系代词用that/which都可以；领先行词是someone，anyone，everyone，somebody，anybody，nobody，everybody，all，those，one〔s〕指人时，关系代词用that，who，whom都可以。
③领先行词被all，much，some，any，〔a〕few，(a) little，no, none, no one等修饰时，只能用that如：I have done all the things that he told us to do. He has no books that I need. ④领先行词是序数词/形容词最高级或被序数词/形容词最高级修饰时，只能用that如：He was the first〔person〕that got to the top of the Mount Qomolangma.He worked out the most difficult problem that I had seen. I like the tallest〔person〕that was asked to come here. ⑤领先行词被the very，the only，the last修饰时，只能用that如：It is the very book that I am looking for. ⑥当主句主语为what, who，which开头的特殊疑问句时，只能用that。
如：Who is the boy that was here just now？Which is the bike that you lost？ ⑦ 主句是There/Here be结构时，当主语指物时，修饰其主语的定语从句用that引导；同时，定语从句局部是there be…句型时，也只能用that引导如：There is still a seat that is free. He asks for a book that there is on the subject. ⑧当句子中有两个以上从句，其中一个已经用了which时，只能用that如：Edison built up a factory which produced things that had never been seen before. ⑨领先行词是主句的表语而引导词又在定语从句中作表语时，只能用that如：China is no longer the country that it used to be.2.只用which引导定语从句的情况： ①作介词的宾语且介词提前的时候〔此时which不可省略〕。
如：This is the house of which the windows face south. ②引导非限制性定语从句的时候〔此时which不可省略〕如：His dog，which was very old，became ill. ③一个句子有两个定语从句时，为了防止重复，一个用that引导，另一个用which引导如：He built up a factory that produce things which had never been seen before. ④先行词为that/those时如：What was that which we saw last night? ⑤先行词后面有插入语时如：The book, I thought, which you lent me yesterday is very expensive.3. as引导定语从句的情况： as可以引导限制性定语从句，也可以引导非限制性定语从句，as在从句中作主语、表语和宾语如：We have found such materials as are used in their factory. (as作主语)These houses are sold at such a low price as people expected. (as作宾语)He is not the same man as he was. (as作表语) ①as引导限制性定语从句的情况：a.领先行词被such, so, as修饰的时候，常用as引导定语从句。
此时应注意与such/so…that引导的结果状语从句区别开来如：He is such a good person as I always dream of making friends with. 〔as引导的定语从句〕He is such a good person that I always dream of making friends with him. 〔such…that引导的结果状语从句〕He is so clever a boy as everyone likes. (as引导的定语从句)He is so clever a boy that every one likes him. (as引导结果状语从句) b.注意the same…as与the same…that引导定语从句的区别：如：This is the same pen as I lent to you. (这和我借给你的那支笔相似)This is the same pen that I lent to you. (这就是我借给你的那支笔) c. 注意：….such as…结构中，such为代词，意为这样的人或物，as在从句中作成分，修饰先行词such的用法。
如：The book is not such as I expect. ②as引导非限制性定语从句时。