“定语从句”知识点的归纳定语从句在整个句子中起着定语的作用，用来修饰名词或代词，被修饰的名词或代词叫做先行词。
定语从句通常放在它所修饰的名词和代词之后。
定语从句通常由关系代词和关系副词引导.一.关系代词有who, whom, whose, that, which等:(注意：whom, that, which在从句中作宾语时可以省略。
)1. who引导的定语从句，修饰人，代替先行词在从句中作主语:The man who came here just now is a painter.He is the student who won the first prize.A cleaner is a person who cleans streets every day .You can’t wake up a person who pretends to be asleep.2. whom 引导的定语从句，修饰人，代替先行词在从句中作宾语:The man ( whom) my father is talking to is my English teacher.Jim is the boy (whom) I borrowed the book from.He is the person (whom) the police are looking for.注: who在非正式英语中也可作宾语, 但可省略,例如:The man (who) you saw is Mr. Green.= The man (whom) you saw is Mr. Green.但是, 如果引导词前面有介词时, 只能用whom, 不能用who:正: The man to whom my father is talking is my teacher.误: The man to who my father is talking is my teacher.3. whose引导的定语从句,可以修饰人也可以修饰物, 代替形容词性的物主代词在从句中作定语，因此，whose的后面通常要跟名词:A child whose parents are both dead is called an orphan.We all hate the boy whose father is very rich and has a car.Please pass me the book whose cover is green.The desk whose leg is broken is very old.4. that 引导的定语从句,可以修饰人也可以修饰物，代替先行词在从句中主语或宾语:Children may do something that makes their parents angry.The letter (that) I got from him was written in English.Do you know the woman that sells eggs?Is he the man (that) you are waiting for?注: that修饰人时,分别可以who和whom替换使用.5. which 引导的定语从句, 修饰物，代替先行词在从句中主语或宾语:The Tea House which was written by Cao YU is my favorite.Another acronym is F2F which means face to face.The story (which) he told made us laugh.Beijing is the place which I was born in.(=Beijing is the place where I was born .)注: which有时可以和替换that使用.二.关系副词有when, where, why等:1. When 引导的定语从句，修饰时间，代替“介词+先行词”在从句中作时间状语。
I will never fgorget the day when I joined the party.She arrived at 12 o’clock when it was raining hard.2. where引导的定语从句，修饰地点，代替“介词+先行词”在从句中作地点状语.This is the house where I was born.He was born in Shanghai where he stayed for 12 years.3.why引导的定语从句，一般只修饰the reason，在从句中表示原因。
This is the reason why he refused to come to the party.三.定语从句要注意的几个问题:1. "介词+ which"结构:关系副词when, where, why的含义相当于"介词+ which"结构，因此常常和"介词+ which"结构替换使用，例如：I will never fgorget the day when I joined the party?→I will never fgorget the day on which I joined the party?She arrived at 12 o’clock when it was raining hard.→She arrived at 12 o’clock at which it was raining hard.This is the house where I was born.→This is the house in which I was born.He was born in Shanghai where he stayed for 12 years.→He was born in Shanghai in which he stayed for 12 years.This is the reason why he refused to join the club.→This is the reason for which he refused to join the club .whose引导的定语从句修饰物时也可以和"介词 + which"结构替换使用，例如：Please pass me the book whose cover is green.→Please pass me the book of which cover is green.The desk whose leg is broken is very old.→The desk of which leg is broken is very old.2. 当which和whom代替先行词在从句作介词的宾语时，介词的位置:a). 介词可以放在原来的位置上,但有时也可以放在which和whom的前面，此时介词后面的关系代词which和whom不能省略。
例如:The man ( whom) my father is talking to is my English teacher. The man to whom my father is talking is my teacher.Jim is the student (whom) I borrowed the book from.Jim is the student from whom I borrowed the book.Beijing is the place (which) I was born in.Beijing is the place in which I was born.b).但固定词组中的介词只能放在原来的位置上，而不能放在which和whom的前面:He is the person (whom) the police are looking for.3.which和that在多数情况下可以相互替换使用,但在下列情形下只能用that作为引导词:a).如果先行词是all, much, anything, something, nothing,everything, little, none等不定代词，关系代词一般只用that:All that we need is money.He told us something that we should do during the vocation.b).序数词或最高级形容词修饰先行词时,关系代词常用that：The first English movie that I saw was Rush Hour.This is the best book that I have ever read.c).如果先等词被some,any, only, few, much, no, very ,last等词修饰，关系代词常用that:That is the only way that leads to your success .d).先行词有两个，一个指人，一个指物，关系代词应该用that:The boy and the dog that are in the picture are very lovely.4.that有时可以代替关系副词 when , where , why和"介词+ which"引导定语从句表示时间．地点或原因，在口语中that常被省略，例如：His father died the year that he was born.= His father died the year when he was born.或His father died the year in which he was born.He can’t find the place that he lived forty years ago.= He can’t find the place where he lived forty years ago.或He can’t find the place in which he lived forty years ago.5.当先行词是时间，地点或原因时，如何选择引导词：此时,引导词的选择主要依据先行词在从句中所起的作用，如果先行词在从句中作主语或者先行词和从句中的动词构成动宾关系时，应选择关系代词that或which作为引导词；若先行词在从句中做地点状语，时间状语或表示原因时，则应选择关系副词 where或when作为引导词. 例如:This is the mountain village where I stayed last year.This is the mountain village (which / that) I visited last year.I'll never forget the days when I worked together with you.I'll never forget the days(which / that) I spent in the countryside.Is this the reason why may explain her absence？Is this the reason that／which may explain her absence？典型错误:This is the mountain village where I visited last year.I will never forget the days when I spent in the countryside.Is this the reason why may explain her absence？6.由于定语从句的结构和用法比较复杂，初学者在使用时往往容易犯一些错误，最常见的有如下七种：a).在定语从句中加了多余的定语。