定语从句的基本用法先请认真阅读下列各句，下列各句中的黑体部分均为该句所包含的定语从句：1.This is the teacher who played basketball with us yesterday.2.Tom is the boy whom they are looking for.3.The house , which they built last year looks very new.4.Physics is the most interesting subject that we learnt in the middle school.从以上各句中我们可以看出定语从句是用来修饰它前面的名词或代词的，它起着修饰或限定作用。
当然定语从句也可以用来修饰一个句子，在此我们不作讨论。
定语从句分为限制性定语从句和非限制性定语从句。
限制性定语从句所修饰的词是一个、一些或一类特定的人或事物，一般不能省略，拿掉后剩下的部分则没有意义，或者表述不清。
非限制性定语从句则不然，它只对所修饰的词作进一步的说明，拿掉以后剩下的部分仍然可以成立，常常用逗号将其隔开。
例如：This is the place where the Chinese Communist Party was founded. 此句中的定语从句是限制性定语从句。
如果拿掉则This is the place.一句没有意义。
This message was left by Xiao Wang, who telephoned you just now. 此句中的定语从句是非限制性定语从句。
如果拿掉则This message was left by Xiao Wang,一句仍有意义。
被定语从句修饰的词叫做先行词，引导定语从句的词称为关系代词或关系副词。
常见的关系代词和关系副词有who, whom,that,whose,which,where,when,why等。
现在我们侧重讨论如何使用这些关系代词和关系副词。
如果关系代词在从句中作主语时一般不能省略，而作宾语时一般可以省略。
一，关系代词who, whom的用法。
1.who可以代替人（即它的先行词必须表示人），在从句中可以担任主语。
也可以在从句中担任宾语，但是它的前面不能带介词，如果带介词则必须使用宾格whom。
whom在从句中只能担任宾语。
例如：a)This is the teacher who often tells us interesting stories in class.b)Mary is the girl who/whom Tom wants to marry.c)Mrs White is a teacher whom every student likes.d)She is the girl with whom I will go to Shanghai tomorrow.2.在定语从句中当先行词表示人时who和that是通用的。
例如：a)Miss Green is the new teacher who/that teaches us spoken English.b)John’s father is an engineer who/that came to see him last Wednesday.但在下列情况下则宜用who 而不用that。
1)先行词是one, ones, anyone时。
如：One who doesn’t study hard in his school time cann’t find a good job in the future. Ones who bought big and nice flat must have a lot of money.Anyone who fails in this test will not be allowed to join in the national test.2) 先行词是those时。
如：Those who want to go to the Great Wall should write the names here.Those who were not fit their work could not see the beautiful clothes made of the magic cloth.3) 先行词是有较长的后置定语修饰时。
如：Yesterday I met a foreigner in a blue shirt who could speak very good Chinese.4)当一个句子中带有两个定语从句时，其中一个定语从句的关系代词用that，而另一个则用who，如：The boy that I met last night is the head of the computer group who studies very hard.5)在there be开头的句子中宜用who。
如：There is an old man who wants to see you.There were two girls who came to school after7:45.二，关系代词whose的用法。
whose是代词的所有格，它既可以代人也可以代物，相当与of whom, of which。
如：Einstein is the world famous scientist whose invention won the Nobel Prize in 1921.= Einstein is the world famous scientist ,the invention of whom won the Nobel Prize in 1921.China is an Asian country whose population is about 1.3 billion.=China is an Asian country, the population of which is about 1.3 billion.三，关系代词that的用法。
首先，要特别注意的是，通常情况下，that只能用于限制性定语从句中，在非限制性定语从句不用that。
另外，介词后面不用that，而用which。
例如：The radio, which（此处不用that，因为它是非限制性定语从句）I bought last week doesn’t work .I gave him a ticket for which(介词后不用that而用which) I paid 15 dollars.在限制性定语从句中that和which在指代物时，一般可以通用，如：The plane that/which has just taken off is half an hour late.在下列情况下，只用that而不用which。
a)当先行词是形容词的最高级，或被形容词的最高级修饰时。
如：This word is the best that is used to answer the question.English is the most useful subject that we learned in the middle school.b)当先行词是序数词，或被序数词修饰时。
如：The USA is the first that sent men to the space.That is the second American film that I have ever seen since I came to this country.c)当主语已有疑问词who或which时。
如：Which is the bike that you lost?Who is the woman that spoke at yesterday’s meeting?d)当先行词既有人又有物时。
如：I don’t know the persons and the things that they are talking about in the hall.e)当先行词是all, much, little, something, everything, anything, nothing, none, theone等词时。
如：You should hand in all that you have.I mean the one that you talked about just now.f)当先行词前面有only, any, few, little, no, all, one of, the same, the very等词修饰时。
如：The only thing that we can do is to give you some money.Li Ming is one of the students that want to be teachers in the future in our class.四，关系副词where, when, why的用法。
a)当先行词表示地点时用where。
可省略。
如：This is the house where Lu Xun was born.=This is the house in which Lu Xun was born.= This is the house that Lu Xun was born..=This is the house Lu Xun was born..b)当先行词表示时间时用when。
可省略。
如：October 1st,1949 was the day when the PRC was founded.= October 1st,1949 was the day on which the PRC was founded.= October 1st,1949 was the day the PRC was founded.= October 1st,1949 was the day that the PRC was founded.c)当先行词表示原因时用why。
可省略。
如：The reason why I’m calling you is to invite you to have dinner with me.= The reason that I’m calling you is to invite you to have dinner with me.= The reason for which I’m calling you is to invite you to have dinner with me.= The reason I’m calling you is to invite you to have dinner with me.专项练习单项选择1．I shall never forget the years ________I lived in the country with the farmers.A. whenB. during thoseC. whichD. where2.Can you tell me the name of the factory _______you visited last week?A. whatB. whereC. whichD. to which3.I don’t know _________ you tell her.A. the wayB. the way in thatC. the way whichD. the way of which4.She heard a terrible noise, ________brought her heart into her mouth. (NMET91)A. itB. whichC. thisD. that5.Is this the restaurant___________?A. which you workB. in which you workC. for which you workD. where you work in6.That tree, the leaves ________are almost yellow, is a very old one.A. whoseB. of whichC. in whichD. on which7.There was nothing ________we could do to stop the traffic accident.A. thatB. \C. whichD. A&B8.He is a man with a large collection of stamps ________gave me a wonderful stamp.A. thatB. whoC. whomD. A&B9. That is one of the books _________are worth reading very much.A. thatB. whichC. from whichD. A&B10.This is the very book_______ I want to find.A. thatB. whichC. itD. with which11.He paid the boy $10 for washing the windows, most of _______hadn’t been cleaned forat least a year. (NMET90)A. theseB. thoseC. thatD. which12.Because of me poor memory, all _______you told me has been forgotten.A. thatB. whichC. whatD. as13.Do you know the girl_________?A. whom he often talkB. he often talks toC. to who he often talks C. so that he often talks14.That is the most difficult problem________ I have ever met.A. thatB. whatC. whichD. whom15. The reason _________ he called you is to ask you to come to our picnic.A. whyB. for thatC. whichD. for why。