二． 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,常可省略.（注：who和whom已无太大区别,基本上可以通用.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.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.
4.that既指人也指物.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 is one million.每年来参观这座城市的人有一百万.
(6) Where is the man that/whom I saw this morning?今天早上我见到的那个人在哪里?
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.他有一个父亲是医生的朋友.
(2) I once lived in a house whose roof has fallen in.我曾经住在一个屋顶塌了的房子里.
whose指物时,常用以下结构来代替
(3) The classroom whose door is broken will soon be repaired.
＝The classroom the door of which is broken will soon be repaired.
(5) Do you like the book whose color is yellow?
＝ Do you like the book the color of which is yellow?
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.先行词通常是"reason".
(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.