用来说明主句中某一名词或代词（有时也可说明整个主句或主句中一部分）而起定语作用的句子叫作定语从句。一词引导的定语从句1. 关系代词用来指代先行词是人或物的名词或代词句子成分 用于限制从句或非限制性从句只用于限制性从句代替人代替物主语Whowhich主语Whomwhich代替人或物thatthat宾语 Whose(=of whom) whose(=of which)例 1： This is the detective who came from London.例 2： The book which I am reading is written by Tomas Hardy.例 3： The desk whose leg is broken is very old.例 4： This is the room that Shakespeare was born in.2关系代词的用法(1) 若是先行词是 all, much, anyt hing, some thing, not hing, every thing, little, none等不定代词，关系代词一样只用that,不用whicho例如：All the people that are present burst into tears.(2) 若是先等词被形容词最高级和 first, last, any, only, few, much, no, some, very等词修饰，关系代词经常使用that,不用which, who,或whom。例如：(3) 非限制性定语从句中，不能用关系代词that,作宾语用的关系代词也不能省略。例如：There are about seven million people taking part in the election, most of who、marewelleducated.(4) which还有一种特殊用法，它能够引导从句修饰前面的整个主句，代替 主句所表示的整体概念或部份概念。在这种从句中，which能够作主语，也能够作宾语或表语，多数情形下意思是与and this相似，并能够指人。例如：He succeeded in the competition, which made his parents very happy.(5) that可指人或物，在从句中作表语，(指人作主语时多用who)仅用于限制性定语从句中。(6) which可作表语，既可指人，以可指物。指人时，一样指从事某种职业 或是有种特点.品性或才能的人Which引导的定语从句能够限制性的，也能够是非限制性的。(7) 若是作先作词的集体名词着眼于集体的整体，关系代词用which;假设是指集体中的各个成员，那么用who。(8) 先行词有两个，一个指人，一个指物，关系代词应该用that。例如：The boy and the dog that are in the picture are very lovely.(9) 若是先行词是 anyone, anybody, everyone, everybody, someone,somebody,关系代词应该用who或whom，不用which。例如：Is there anyone here who will go with you?Where:关于关系副词where的考察，趋于一种“地址的模糊化”。当先行词表示某人/物的sit ua tion,或某事进展的st age，或表达某事的某个方面时都可用关系副词where。常见的先行词还有point，case等。3“介词关系代词“是一个普遍利用的结构(1) “介词关系代词“能够引导限制性定语从句，也能够引导非限制性定 语从句。“介词关系代词“结构中的介词能够是 in, on, about, from, for, with, to at, of, without等，关系代词只可用whom或which,不可用that。in which =wherefor which =whyon which = when(2) from where为“介词+关系副词“结构，但也能够引导定语从句。例如：We stood at the top of the hill, from where we can see the town.等固定短语动词，在定语从句中一样不宜将介词与动词分开。例如：This is the boy whom she has taken care of.二关系副词引导的定语从句1关系副词也能够引导定语从句关系副词在从句中别离表示时刻.地址或缘故。关系副词when在从句中充那时刻状语，where充本地址状语，why充当缘故状语。2. that可引导定语从句表示时刻.地址或缘故That有时能够代替关系副词when, where或why引导定语从句表示时亥【.地址或缘故，在that引导的这种定语从句中，that也能够省去。三限制性定语从句与非限制性定语从句1二者差异比较限制定语从句紧跟先行词，同先行词这间一般不加逗号，仅修饰先行词，可以由关系代词.关系副词或that来引导。非限制性定语从句仅作补充或说明，用逗号与主句隔开，既可修饰先行词，又可修饰整个主句，不可用that引导。2关系代词和关系副词的选择依据 (1)弄清代替先行词的关系词在从句中作什么成分,作状语的应选用关系副 词，作主语宾语或表语的可选用关系代词。3. 先行词与定语从句隔离定语从句一般紧跟在先行词之后，但定语从句与先行词之间有时也会插入别的成分，构成先行词与定语从句的隔离。例如：1) This is the article written by him that Is poke to you about.2) He was the only person in this country who was invited四.As在定语从句中的用法1. 引导限制性定语从句和非限制性定语从句1)as 多与 such 或 the(2) as也可单独使用，引导非限制性定语从句，作用相当于which。例如：The elephants nose is like a snake, as anybody can see.3) the samethat与the same *as在意思上是不同的。2. As引导的非限制性定语从句的位置as引导的非限制性定语从句位置较灵活，能够位于主句前面.中间或后面,一样用逗号与主句隔开，但which所引导的非限制性定语从句只能放在主句以后as is know n 众所周知，as is of ten the case 情形常常如此，as is supposed如所料想的，as of ten happens这种情形常常发生，as is expec ted在意料当中。例如：(1) As is expected, the England team won the football match.(2) The earth runs around the sun, as is known by everyone.众所周知, 定语从句能够分为限制性定语从句和非限制性定语从句。下面结合考 例谈谈学习运用非限制性定语从句时应注意的几个问题：、that不能用来引导非限制性定语从句。如：【考例一】She heard the terrible noise,brought her heart intoher mouth.A. it B. which C. this D. that【解析】选B。后半句为非限制性定语从句，尽管先行词noise属于事物，也不能用that而要用which来引导。which指代noise，在从句中作主语。二、除which外，还可用when，where，whose，whom等引导非限制性 定语从句，且各自的用法及差异与它们用在限制性定语从句时相同。如：Next month, when youll spend your summer holidays in your hometown, is approaching. 下个月即将来临，届时你们将在家乡度暑假。（关 系副词when指代表示时间的名词next month，并作从句的状语。）She is going to live in Macao, where she has some close friends.她要至U 澳门去居住，在那里她有几个密友。（关系副词where指代表示地址的名词Macao ,并在从句中作状语。）【考例二】Recently I bought an ancient Chinese vase,was veryreasonable.A. which priceB. the price of whichC. its priceD. the price of whose【解析】选B。whose在从句中作表示所属关系的定语，既可指代人，也可指代物。指物时，常可转换为of which ;指人时常可转换为of whom。【考例三】 In the office I never seem to have time until after 5:30 pm,many people have gone home.A. whose time B. thatC. on which D. by which time【解析】先行词5:30 pm与time之间是一种同位关系，可用which来作定 语替代。从句中的完成状态，常与by短语连用。故选D。三、在非限制性定语从句中作宾语的关系代词不能省略。如：He was eager to go to the hospital to see his stepmother, whom heloved as his own mother. 他迫切地想到医院去看望他的继母，他把继母当自己的亲妈妈一样爱戴。四、非限制性定语从句的关系代词which，既能够指代前面的先行词，也能够 指代前面整句的含义。如：【考例四】 Dorothy was always speaking highly of her role in the play, of course,made the others unhappy.A. who B. whichC. this D. what【解析】选B。指代“Dorothy总是高度评价自己在那场戏中所担任的角色” 的整个事件。【考例五】Carol said the work would be done byOctober,personally I doubt very much.A. it B. thatC. when D. which【解析】表示时间的名词October,用“我个人非常怀疑”来修饰，意思不 通。应该修饰整个主句，表示对“Carol说在十月前能做好这项工作”怀疑。 故选 D。五、引导非限制性定语从句时as和which的差异：从句置于句首时，非限制性定语从句只能用as引导，而置于句末时，两者都可以使用。如：【考例六】is known to everybody, the moon travels round theearth once every month.A. It B. As C. That D. Wha