Question

what，which，who，whom分别可做什么

Answer 1

（一） 限定性定语从句　　一、关系代词（在句中作主语、宾语或定语）
　　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在从句中作宾语也可以省略。[eg：this is the book （which）you want。]
　　2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
　　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 , none等不定代词时，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 还有先行词前有序数词或形容词最高级修饰时,或先行词就是序数词或最高级时.以及先行词中既有人又有物时.还有句中前面有which时,都只能用that
　　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. 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。
　　二、关系副词（在句中作状语）
　　关系副词=介词+关系代词
　　why=for which
　　where=in/ at/ on/ ... which (介词同先行词搭配)
　　when=during/ on/ in/ ... which (介词同先行词搭配)
　　1. where是关系副词，用来表示地点的定语从句。
　　2. 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 towels, soap, toothbrush etc。
　　3. 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,whose代表事物，如果需要用why，
　　可用for which代替.； [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. 在踢足球的男孩们是一班的.
　　(2) Yesterday I helped an old man who lost his way. 昨天，我帮助了一个迷路的老人.
　　2. whom指人，在定语从句中充当宾语，常省略。（注：who和whom已无太大区别，基本可以通用。唯一区别是who可以做主语而whom不可以。）
　　(1) Mr. Liu is the person (whom) you talked with on the bus. 刘先生就是在公交车上和你聊天的那个人.
　　(2) Mr. Ling is just the boy whom I want to see. 凌先生恰巧就是我想见的那个男孩.
　　(3) The man who/whom you met just now is my friend. 你刚刚见到的那个人就是我的朋友.
　　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。
　　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. 他就是那个和我聊天的男人.
　　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. 他就是那个有英语书的男人.
　　3. 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?
　　4.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. 足球是大多数男孩都喜欢的游戏.
　　(2) This is the pen (which) he bought yesterday. 这是他昨天刚买的钢笔.
　　5. 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? [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.
　　= The school in which he once studied is very famous.
　　(2) Tomorrow I will bring here a magazine (that/which) you asked for.
　　= Tomorrow I will bring here a magazine for which you asked.
　　(3) We’ll go to hear the famous singer (whom/that/who) we have often talked about.
　　= 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
　　T This is the watch which/that I am looking for. (T＝正确)
　　F 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)
　　The man with that you talked is my friend. (F)
　　(2) The plane in which we flew to Canada is very comfortable. (T)
　　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.
　　关系代词
　　关系代词（一般情况下）that 可用who ,whom 和which在从句做主语，谓动词的宾语，但是不能做介词的宾语。
　　which指物，在从句中作主语，谓语或宾语；
　　who在从句中作主语；
　　whom在从句中宾语；
　　where在从句中修饰表地点的名词，做地点状语；
　　when在从句中通常修饰表时间的名词，做时间状语；
　　why在从句中做原因状语，先行词通常是"reason"
　　有时why也可用for+which代替。
　　例：A doctor is a person who looks after people's health.
　　______ _ _____ _____________________
　　主语 谓语 先行词 从句
　　|________________________|
　　定语从句修饰先行词 [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. [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，is后应跟表语，只有the one可以，而后面的you visited a few days ago则做one的定语从句。
　　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. [编辑本段]（八）先行词和关系词二合一　　　1)Whoever spits in public will be punished here.　(Whoever 可以用 anyone who 代替)　2)The parents will use what they have to send their son to technical school. (what 可以用all that代替)
　　但这两句句子已经不是定语从句了，是名词性从句。因为定语从句一定要有先行词，而名词性从句没有。将“Whoever”、“what”分别用“Anyone who”、“all that”代替后，才是定语从句，先行词分别是“Anyone”、“all”。
　　（九）as,which引导的非限制性定语从句　由as, which 引导的非限定性定语从句，as和which可代整个主句，相当于and this或and that。As一般放在句首，which在句中。　
　　As we know, smoking is harmful to one's health.　
　　The sun heats the earth, which is very important to us.　
　　典型例题
　　1）Alice received an invitation from her boss, ___came as a surprise.
　　A. it　B. that　C. which　D. he　
　　答案C。
　　此为非限定性从句，不能用 that修饰，而用which.，it 和he 都使后句成为句子，两个独立的句子不能单以逗号连接。况且选he句意不通。
　　2）The weather turned out to be very good, ___ was more than we could expect.
　　A. what　B. which　C. that　D. it　
　　答案B。
　　which可代替句子，用于非限定性定语从句，而what不可。That 不能用于非限定性定语从句，it不为连词，使由逗号连接的两个句子并在一起在英语语法上行不通。
　　3）It rained hard yesterday, ____ prevented me from going to the park..
　　A. that　B. which　C. as　D. it　
　　答案B。　　
　　as 和which在引导非限制性定语从句时，这两个关系代词都指主句所表达的整个意思，且在定语从句中都可以作主语和宾语。但不同之处主要有两点：　
　　(1） as 引导的定语从句可置于句首，而which不可。　
　　(2） as 代表前面的整个主句并在从句中作主语时，从句中的谓语必须是系动词；若为行为动词，则从句中的关系代词只能用which.。　
　　在本题中，prevent由于是行为动词，所以正确选项应为B。
　　As 的用法例
　　1. the same… as；such…as 中的as 是一种固定结构, 和……一样……。　
　　I have got into the same trouble as he (has).
　　例2. as可引导非限制性从句，常带有'正如'。　
　　As we know, smoking is harmful to one's health.　
　　As is known, smoking is harmful to one's health.　
　　As是关系代词。例1中的as作know的宾语；
　　例2中，它充当从句的主语，谓语动词know要用被动式。

Answer 2

（一） 限定性定语从句　　一、关系代词（在句中作主语、宾语或定语）
　　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在从句中作宾语也可以省略。[eg：this is the book （which）you want。]
　　2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
　　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 , none等不定代词时，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 还有先行词前有序数词或形容词最高级修饰时,或先行词就是序数词或最高级时.以及先行词中既有人又有物时.还有句中前面有which时,都只能用that
　　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. 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。
　　二、关系副词（在句中作状语）
　　关系副词=介词+关系代词
　　why=for which
　　where=in/ at/ on/ ... which (介词同先行词搭配)
　　when=during/ on/ in/ ... which (介词同先行词搭配)
　　1. where是关系副词，用来表示地点的定语从句。
　　2. 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 towels, soap, toothbrush etc。
　　3. 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,whose代表事物，如果需要用why，
　　可用for which代替.； [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. 在踢足球的男孩们是一班的.
　　(2) Yesterday I helped an old man who lost his way. 昨天，我帮助了一个迷路的老人.
　　2. whom指人，在定语从句中充当宾语，常省略。（注：who和whom已无太大区别，基本可以通用。唯一区别是who可以做主语而whom不可以。）
　　(1) Mr. Liu is the person (whom) you talked with on the bus. 刘先生就是在公交车上和你聊天的那个人.
　　(2) Mr. Ling is just the boy whom I want to see. 凌先生恰巧就是我想见的那个男孩.
　　(3) The man who/whom you met just now is my friend. 你刚刚见到的那个人就是我的朋友.
　　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。
　　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. 他就是那个和我聊天的男人.
　　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. 他就是那个有英语书的男人.
　　3. 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?
　　4.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. 足球是大多数男孩都喜欢的游戏.
　　(2) This is the pen (which) he bought yesterday. 这是他昨天刚买的钢笔.
　　5. 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? [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.
　　= The school in which he once studied is very famous.
　　(2) Tomorrow I will bring here a magazine (that/which) you asked for.
　　= Tomorrow I will bring here a magazine for which you asked.
　　(3) We’ll go to hear the famous singer (whom/that/who) we have often talked about.
　　= 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
　　T This is the watch which/that I am looking for. (T＝正确)
　　F 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)
　　The man with that you talked is my friend. (F)
　　(2) The plane in which we flew to Canada is very comfortable. (T)
　　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.
　　关系代词
　　关系代词（一般情况下）that 可用who ,whom 和which在从句做主语，谓动词的宾语，但是不能做介词的宾语。
　　which指物，在从句中作主语，谓语或宾语；
　　who在从句中作主语；
　　whom在从句中宾语；
　　where在从句中修饰表地点的名词，做地点状语；
　　when在从句中通常修饰表时间的名词，做时间状语；
　　why在从句中做原因状语，先行词通常是"reason"
　　有时why也可用for+which代替。
　　例：A doctor is a person who looks after people's health.
　　______ _ _____ _____________________
　　主语 谓语 先行词 从句
　　|________________________|
　　定语从句修饰先行词 [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. [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，is后应跟表语，只有the one可以，而后面的you visited a few days ago则做one的定语从句。
　　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. [编辑本段]（八）先行词和关系词二合一　　　1)Whoever spits in public will be punished here.　(Whoever 可以用 anyone who 代替)　2)The parents will use what they have to send their son to technical school. (what 可以用all that代替)
　　但这两句句子已经不是定语从句了，是名词性从句。因为定语从句一定要有先行词，而名词性从句没有。将“Whoever”、“what”分别用“Anyone who”、“all that”代替后，才是定语从句，先行词分别是“Anyone”、“all”。
　　（九）as,which引导的非限制性定语从句　由as, which 引导的非限定性定语从句，as和which可代整个主句，相当于and this或and that。As一般放在句首，which在句中。　
　　As we know, smoking is harmful to one's health.　
　　The sun heats the earth, which is very important to us.　
　　典型例题
　　1）Alice received an invitation from her boss, ___came as a surprise.
　　A. it　B. that　C. which　D. he　
　　答案C。
　　此为非限定性从句，不能用 that修饰，而用which.，it 和he 都使后句成为句子，两个独立的句子不能单以逗号连接。况且选he句意不通。
　　2）The weather turned out to be very good, ___ was more than we could expect.
　　A. what　B. which　C. that　D. it　
　　答案B。
　　which可代替句子，用于非限定性定语从句，而what不可。That 不能用于非限定性定语从句，it不为连词，使由逗号连接的两个句子并在一起在英语语法上行不通。
　　3）It rained hard yesterday, ____ prevented me from going to the park..
　　A. that　B. which　C. as　D. it　
　　答案B。　　
　　as 和which在引导非限制性定语从句时，这两个关系代词都指主句所表达的整个意思，且在定语从句中都可以作主语和宾语。但不同之处主要有两点：　
　　(1） as 引导的定语从句可置于句首，而which不可。　
　　(2） as 代表前面的整个主句并在从句中作主语时，从句中的谓语必须是系动词；若为行为动词，则从句中的关系代词只能用which.。　
　　在本题中，prevent由于是行为动词，所以正确选项应为B。
　　As 的用法例
　　1. the same… as；such…as 中的as 是一种固定结构, 和……一样……。　
　　I have got into the same trouble as he (has).
　　例2. as可引导非限制性从句，常带有'正如'。　
　　As we know, smoking is harmful to one's health.　
　　As is known, smoking is harmful to one's health.　
　　As是关系代词。例1中的as作know的宾语；
　　例2中，它充当从句的主语，谓语动词know要用被动式。

追问

有没有简单些的啊

Answer 3

what，which，who，whom 这些都是疑问词还是关系代词？
要做什么取决于你所要应用到什么句子中啊！！！！

Answer 4

分别可以做主语，宾语，定语，状语，补语，独立成分。

追问

谢谢！

Answer 5

都可以作疑问代词连接代词关系代词 并在句子中起代词作用。