The boys who are playing football are from Class One.
Those who want to go to the museum must be at the school gate at 7 tomorrow morning.
Yesterday I helped an old man who had lost his way.
（三）“介词+关系代词”引 导的定语从句
关系代词在定语从句中作介词 宾语时，从句常常由“ห้องสมุดไป่ตู้词+ 关系代词”引出。
The school (which / that) he once studied in is very famous.
The school in which he once studied is very famous.
4．that 指人时，相当于 who 或 whom；指物时，相当于 which。在定语从句中作主语 或宾语，作宾语时常可省略。
The number of people that / who come to visit this city each year reaches one million.
Where is the man that / whom I saw this morning?
The person that /whom you introduced to me is very kind.
The season that / which comes after spring is summer.
The classroom the door of which is broken will soon be repaired.
Do you like the book whose cover is yellow?
Do you like the book the cover of which is yellow?
This is the boy with whom I played tennis yesterday.
We’ll go to hear the famous singer (whom / who / that) we have often talked about.
Tomorrow I’ll bring here the magazine (which / that) you asked for.
Tomorrow I’ll bring here the magazine for which you asked.
This is the boy (whom / who / that) I played tennis with yesterday.
关系副词有: when, where, why
关系词通常有下列三个作用：
A.引导定语从句； B.代替先行词； C.在定语从句中担当一个成分。
The man who is shaking hands with my father is a policeman.
（二）关系代词引导的定语从句
1.who 指人，在定语从句中 作主语。
Yesterday I received a letter that / which came from Australia.
5. whose 通常指人，也可指物， 在定语从句中做定语。
I visited a scientist whose name is known all over the country.
He likes to read books which are written by foreign writers. The house which is by the lake looks nice. This is the pen ( which ) he bought yesterday. The film ( which ) they went to see last night was not interesting at all.
（一）定义及相关术语
1.定语从句： 修饰某一名词或代词的从句叫定语 从句。定语从句一般紧跟在它所修 饰的先行词之后。
2.先行词： 被定语从句修饰的词叫先行词。 3.关系词： 引导定语从句的词叫关系词。
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
The professor ( whom ) you are waiting for has come.
The girl ( whom ) the teacher often praises is our monitor.
注意：关系代词 whom 在口语 或非正式文体中常可用 who 来代替，也可省略。
That is the teacher who teaches us physics.
2. whom 指人，在定语从句中 做宾语，常可省略。
Mr Liu is the person ( whom ) you talked about on the bus.
Li Ming is just the boy ( whom ) I want to see.
He has a friend whose father is a doctor.
I once lived in the house whose roof has fallen in.
注意：指物时，常用下列结构 来代替：
The classroom whose door is broken will soon be repaired.
The man ( whom / who ) you met just now is my old friend.
3. which 指物，在定语从句中 做主语或宾语，做宾语时常可 省略。
Football is a game which is liked by most boys.
The factory which makes computers is far away from here.