1. that既可代表事物也可代表人，which代表事物；它们在从句中作主语或宾语，that在从句中作宾语时常可省略关系词，which在从句中作宾语则不能省略。而且，如果which在从句中作“不及物动词＋介词”的介词的宾语，注意介词不要丢掉，而且介词总是放在关系代词which的前边，但有的则放在它原来的位置 2. which作宾语时，根据先行词与定语从句之间的语义关系，先行词与which之间的介词不能丢 3. 代表物时多用which，但在带有下列词的句子中用that而不用which，这些词包括当先行词是anything, everything, nothing ,few, all, none, little, some等代词时，或者是由every, any, all, some, no, little, few, much等修饰时等，这时的that常被省略 4. who和whom引导的从句用来修饰人，分别作从句中的主语和宾语，whom作宾语时，要注意它可以作动词的宾语也可以作介词的宾语 5. where是关系副词，用来表示地点的定语从句 6. when引导定语从句表示时间〔注〕值得一提的是，表示时间“time"一词的定语从句只用when引导，有时不用任何关系代词，当然也不用that引导 By the time you arrive in London, we will have stayed there for two weeks. I still remember the first time I met her. Each time he goes to business trip, he brings a lot of living necessities, such as towers, soap, toothbrush etc. 7. whose是关系代词，修饰名词作定语，相当于所修饰成分的前置所有格.它引导的从句可以修饰人和物, 当它引导的从句修饰物体时, 可以与 of which 调换,表达的意思一样. 8. 当从句的逻辑主语是some, any, no, somebody, anybody, nobody, something, anything, everything或nothing时，常用there is来引导 There is somebody here who wants to speak to you. 这里有人要和你说话。 编辑本段（二）非限定性定语从句 非限定性定语从句的作用是对所修饰的成分作进一步说明，通常是引导词和先行词之间用逗号隔开，将从句拿掉后其他部分仍可成立 1. which引导的非限定性定语从句来说明前面整个句子的情况或主句的某一部分 2.当先行词是专有名词或物主代词和指示代词所修饰时，其后的定语从句通常是非限制性的，例如： Charles Smith, who was my former teacher, retired last year. 查理·史密斯去年退休了，他曾经是我的老师。 My house, which I bought last year, has got a lovely garden. 我去年买的的那幢房子带着个漂亮的花园。 This novel, which I have read three times, is very touching. 这本小说很动人，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, 这时从句谓语动词要用第三人称单数，例如： He seems not to have grasped what I meant, which greatly upsets me. 他似乎没抓住我的意思，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。 4. 有时as也可用作关系代词 5. 在非限定性定语从句中，不能用关系副词why和关系代词that，而用who, whom代表人，用which代表事物.； 编辑本段（三）关系代词引导的定语从句 1.who指人，在从句中做主语 (1) The boys who are playing football are from Class One. (2) Yesterday I helped an old man who lost his way. 2. whom指人，在定语从句中充当宾语，常可省略。 (1) Mr. Liu is the person (whom) you talked about on the bus. (2) Mr. Ling is just the boy whom I want to see. 注意：关系代词whom在口语和非正式语体中常用who代替，可省略。 (3) The man who/whom you met just now is my friend 3.which指物，在定语从句中做主语或者宾语，做宾语时可省略 (1) Football is a game which is liked by most boys. (2) This is the pen (which) he bought yesterday. 如果在从句中做宾语,就用whom或who.比如: He is the man whom/who I talk to. 如果是在从句中作主语就只能用who.比如: He is the man who has an English book. 4. that指人时，相当于who或者whom；指物时，相当于which。 在定语从句中做主语或者宾语，做宾语时可省略。 (5) The number of the people that/who come to visit the city each year rises one million. (6) Where is the man that/whom I saw this morning? 5. whose通常指人，也可指物，在定语从句中做定语 (1) He has a friend whose father is a doctor. (2) I once lived in a house whose roof has fallen in.whose指物时，常用以下结构来代替 (3) The classroom whose door is broken will soon be repaired. (4) The classroom the door of which is broken will soon be repaired. (5) Do you like the book whose color is yellow? (6) Do you like the book the color of which is yellow? 编辑本段（四）注意 介词+关系代词引导的定语从句关系代词在定语从句中做介词宾语时 从句常由介词+关系代词引导 (1) The school (that/which) he once studied in is very famous. (2) The school in which he once studied is very famous. (3) Tomorrow I will bring here a magazine (that/which) you asked for. (4) Tomorrow I will bring here a magazine for which you asked. (5) We’ll go to hear the famous singer (whom/that/who) we have often talked about. (6) We’ll go to hear the famous singer about whom we have often talked. 注意：1. 含有介词的动词短语一般不拆开使用，如：look for, look after, take care of等 (1) This is the watch which/that I am looking for. (T＝正确) (2) This is the watch for which I am looking. (F＝错误) 2. 若介词放在关系代词前，关系代词指人时用whom，不可用who或者that；指物时用which，不能用that；关系代词是所有格时用whose (1) The man with whom you talked is my friend. (T) (2) The man with that you talked is my friend. (F) (3) The plane in which we flew to Canada is very comfortable. (T) (4) The plane in that we flew in to Canada is very comfortable. (F) 3. “介词+关系代词”前可有some, any, none, both, all, neither, most, each, few等代词或者数词 (1) He loved his parents deeply, both of whom are very kind to him. (2) In the basket there are quite many apples, some of which have gone bad. (3) There are forty students in our class in all, most of whom are from big cities. 编辑本段（五）关系副词引导的定语从句 1. when指时间，在定语从句中做时间状语 (1) I still remember the day when I first came to the school. (2) The time when we got together finally came. 2. where指地点，在定语从句中做地点状语 (1) Shanghai is the city where I was born. (2) The house where I lived ten years ago has been pulled down. 3. why指原因，在定语从句中做原因状语 (1) Please tell me the reason why you missed the plane. (2) I don’t know the reason why he looks unhappy today. 注意：关系副词引导的从句可以由“介词+关系代词”引导的从句替换 (1) The reason why/ for which he refused the invitation is not clear, (2) From the year when/in which he was going to school he began to know what he wanted when he grew up. (3) Great changes have taken place in the city in which./where I was born. 编辑本段（六）判断关系代词与关系副词 方法一： 用关系代词，还是关系副词完全取决于从句中的谓语动词。不及物动词后面无宾语，就必须要求用关系副词或者是介词加关系代词；而及物动词后接宾语，则要求用关系代词。例如： This is the mountain village where I stayed last year. I'll never forget the days when I worked together with you. 判断改错（注：先显示题，再显示答案，横线；用不同的颜色表示出。） （错） This is the mountain village where I visited last year. （错） I will never forget the days when I spent in the countryside. （对） This is the mountain village (which) I visited last year. （对） I'll never forget the days (which) I spent in the countryside. 习惯上总把表地点或时间的名词与关系副词 where, when联系在一起。此两题错在关系词的误用上。 方法二： 准确判断先行词在定语从句中的成分(主、谓、宾、定、状)，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 ago? 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变为肯定句： This museum is ___ you visited a few days ago.例2变为肯定句： This is the museum ___ the exhibition was held. 在句1中，所缺部分为宾语，而where, that, on which都不能起到宾语的作用，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点，既可用副词where，又因 in the museum词组，可用介词in + which 引导地点状语。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 (who, whom, that, which, whose)； 先行词在从句中做状语时，应选择关系副词 ( where 地点状语，when 时间状语，why 原因状语) 。 编辑本段（七）介词+关系词 1）介词后面的关系词不能省略。 2）that前不能有介词。 3） 某些在从句中充当时间，地点或原因状语的"介词+关系词"结构可以同关系副词when ,where和why 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? This is the reason why he came late. This is the reason for which he came late

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定语：定语是对名词或代词起修饰、限定作用的词、短语或句子，汉语中常用‘……的’表示。 定语通常位于被修饰的成分前。若修饰some,any,every,no构成的复合不定代词时，（如：something、nothing）；或不定式、分词短语作定语、从句作定语时，（也称为定语从句）则定语通常置后。副词用作定语时须放在名词之后。例如 The boy who is reading needs the pen which you bought yesterday. 那个在阅读的男孩需要你昨天买的钢笔。 在这个句子中，the boy 是句子的主语，跟在他后边的 who is reading 就是boy 的定语从句，修饰那个男孩所处的状态。