1.关系词：引导定语从句的关联词称为关系词,关系词有关系代词和关系副词.关系代词有that, which, who, whom, whose, as等；关系副词有where, when, why等.
2.关系代词:who, whom, whose 或that
作主语的一般用who或that
作宾语的一般用whom, who或that,
作定语并具有物主性质的用whose.（在定语从句中作宾语的关系代词可省略）
如：
①I don’t like people who/that get angry easily.
我不喜欢容易发脾气的人.
（ 关系代词who/ that在定语从句中作主语,不可省略）
②Here is the man (whom/ who/ that) you want to see.
这就是你想见的人.
（ 关系代词whom/ who/ that在定语从句中作宾语,可以省略）
③Is there anyone in your class whose home is in the northeast?
你班上有谁家在东北的?
（ 关系代词whose在定语从句中作定语,不能省略）
注意：用who 还是whom ,完全根据它们本身在定语从句中的地位和作用而定,与先行词在主句中的作用无关.尤其要注意在带有插入语的定语从句中who和whom的选用.
如：
①The person who sent the letter had to pay the postage.
寄信人要付邮资.
（ who sent the letter是定语从句,修饰person, who在定语从句中作主语,因此用主格）
②He is a man who I believe is honest.
他是一个我认为诚实的人.
（ I believe是插入语,去掉该插入语剩下的便是He is a man who is honest,在语法及句意上都能成立,who是定语从句中动词is的主语,故用主格,不用宾格whom.）
⒉ 如果修饰事物,用关系代词which 和that,作宾语时可省略.作介词宾语时,如果介词位于关系代词之前,则用which (不能省) ,而不用that（关系代词that既能代人,又能代物）.whose也可用来指物（此时可用of which来代替）,在定语从句中作定语.
如：
①Don’t buy tomatoes that/ which are green.
不要买颜色还是青的西红柿.
( that/ which 在定语从句中作主语,不能省)
②The fish (that/ which) they sell are not fresh.
他们卖的鱼不新鲜.
（ that/ which 在定语从句中作宾语,可以省）
③The classroom whose door is broken will soon be repaired.
= The classroom the door of which is broken will soon be repaired.
门坏了的那个教室将很快修理.
④The tool with which he is working is called a saw.
=The tool (that/ which) he is working is called a saw.
他干活用的那个工具叫叫锯.
（介词with位于关系代词之前,须用which,不能省,也不能用that）
二 定语从句中关系副词的选用
⒈ when指时间,在定语从句中作时间状语,有时也可用介词+which来代替.
如：
I still remember the day when / on which I first came to Beijing.
我还记得我第一次来到北京那天的情景.
She came at a time when we needed her most.
她是在我们需要她的时候来的.
⒉ where指地点,在定语从句中作地点状语,有时也可用介词+which来代替.
如：
That is the housewhere/ in which he lived ten years ago.
那是他十年前住过的房子.
I have found a peaceful place where/ in which we can study.
我找到了一个能学习的安静的地方.
⒊ why指原因,在定语从句中作原因状语,常可用for+ which来代替.
如：
I know the reason why/ for which she was so angry.
我知道她为什么那么生气.
Do you know the reason why/for which he came so late?
你知道他来得这么晚的原因吗?
◆应注意关系副词和关系代词在定语从句中的不同使用.
如：
* I’ll never forget the day when I went abroad myself.
我永远忘不了我独自出国的那一天.
( when在从句中代替时间状语on the day,我们可以把这个句子分解为I’ll never forget the day. I went abroad myselfon the day.)
* We’ll never forget the days that we spent together.
我们永远也不会忘记我们在一起度过的那些日子.
(that 代替the day,在句中作spent的宾语,that可以省略.该句可分解为We’ll never forget the days. We spent the days together.)
三 way 作先行词之后的定语从句
当“way”表示“方式、方法”在句中作先行词,后被一个定语从句修饰时,引导定语从句可用that ,也可用in which,或什么都不用.
如：
I don’t like the way that he laughed at me.
=I don’t like the way in which he laughed at me.
=I don’t like the way he laughed at me.
我不喜欢他用那种方式来嘲笑我.
四 time 之后的定语从句
time作先行词,前面如有序数词和last修饰时,引导定语从句不能用when,只能用that 或两者都不用.但前面如无序数词或last,常用when(有时也用that)引导定语从句.
如：
This is the last time that I shall give you a lesson.
这是我最后一次给你们上课.
The first time I saw Premier Zhou was in 1958.
我第一次见周总理是在1958年.
I don’t know the exacttime when the track and field meet will take place.
我不知道田径运动会举行的确切时间.
3.关系副词=介词+关系代词
why=for which where=in which when=during which whose=of which
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
3. 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.
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
eg. I still remember the day when I first came to the school.
2. where指地点,在定语从句中做地点状语
eg. Shanghai is the city where I was born.
3. why指原因,在定语从句中做原因状语
eg. Please tell me the reason why you are late.
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.
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.
（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
例2. Is this the museum ____ the exhibition was held?
A. where B. that C. on which
关系词的选择依据在从句中所做的成分,○1先行词在从句中做主、定、宾语时,选择关系代词 (who, whom, that, which, whose)；○2 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) .
