要学定语从句，得知道什么是定语。定语是用来限定、修饰名词或代词的。例如，a good book,
good就是定语。那么复合句中修饰名词或代词的从句就叫做定语从句。定语从句由关系代词或关系副词引导，相当于形容词，在句中作定语。
英语从句中的句型结构比较复杂，有先行词、关系代词或关系副词。
被定语从句修饰的词叫先行词，定语从句一般放在先行词的后面。The man who / that I saw at the school gate
yesterday is my English teacher.先行词 定语从句昨天我在校门口看见的那个人是我的英语老师。
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等，绝对没有what;关系副词有where, when, why,how等。
关系词放在先行词和定语从句之间，起连接作用，同时又作定语从句的某个成分。I am waiting for the boy who /that is
wearing a red coat. (主语)先行词 关系代词我正在等穿着红色外套的那个男孩。
The dictionary that / which my sister gave me last Sunday is very
expensive.(宾语)先行词 关系代词我姐姐上周星期天给我的那本字典很贵。
The woman is his mother whose name is Linda Brown. (定语)先行词
That is the house where my father used to live.(状语)先行词
1. who指人(也可用that)，在定语从句中作主语，也可作宾语。如：
Yesterday I helped an old man who / that lost his way. (主语)昨天我帮助了一位迷路的老人。Mr
Wang is the man (who / that / whom )you met in the zoo this morning.(宾语)
王先生就是今天早上你在动物里遇到的那个人。注意：关系代词who指人,作宾语时，可用whom代替;作宾语时，关系代词可省略。作其它成分，关系代词则不能省略。
2. whose指人，也可指物。在定语从句中作定语。The boy whose mother is ill is staying at home to
look after her today.其母亲生病的那个男孩今天呆在家里照顾她。I have a story book whose cover is red.
3. which指物(也可用that)，在定语从句中作主语，也可作宾语。如：Football is a game which / that is
liked by most boys. (主语)足球是被大多数男孩喜欢的运动。I don’t believe the news which / that Tom
won the game. (同位语我不相信汤姆赢得这场比赛的消息。
关系代词whom, which在定语从句中作介词宾语时，可以和介词一起放在先行词与定语从句之间。
That is the place in which I lived for five years.=That is the place which
/ that I lived in for five years.那就是我住过五年的地方。Mr Zhang is the man for whom I am
looking.=Mr Zhang is the man who / whom / that I am looking
for.张先生就是我正在找的那个人。
注意：1. 含有介词的动词短语一般不拆开使用，如：look for, look after, take care of等 (1) this is
the watch which/that i am looking for.(正确)(2) this is the watch for which i am
looking.(错误)
2. 若介词放在关系代词前，关系代词指人时用whom，不可用who或者that;指物时用which，不能用that; (1) the man with
whom you talked is my friend.(正确) (2) the man who/that you talked with is my
friend.(正确)(3) the plane in which we flew to canada is very comfortable. (正确)
(4) the plane in that we flew in to canada is very comfortable. (错误)
3."介词+关系代词"前可有some, any, none, both, all, neither, most, each, few等代词或者数词
(1) he loved his parents deeply, both of whom are very kind to him. (2) in the
basket there are quite many apples, some of which have gone bad. (3) there are
forty students in our class in all, most of whom are from big cities.
"类型的定语从句题时，关键在于分析定语从句中的谓语动词(该动词是不及物动词)习惯上常与什么介词搭配使用。这就需要同学们在平时学习时要注重某些不及物动词和介词惯用的情形，并要灵活运用。
例如：in the dark street, there wasn't a single person ________ she could turn
for help.a. that b. who c. from whom d. to whom简析:本题定语从句中的turn 与介词 to
构成固定短语"turn to sb. for help (向某人求助)"。所以，d是正确选项。
1. 先行词是地点时，如果该先行词做了定语从句的主语或宾语时，关系代词用that或which. 如：
The school that / which I used to study in is becoming better and
better.(the school
作了介词in的宾语。)我过去曾经学习的那所学校变得越来越好了。先行词是地点时，如果该先行词不作定语从句的主语或宾语时，关系代词用where. 如：The
place where the accident happened isn’t far from our
school.事故发生的那个地方离我们学校不远。(定语从句中的动词happened是不及物动词，它不跟宾语，而the
accident又作了定语从句的主语，因此该定语从句既不需要主语，也不需要宾语。)
2.只用that，不用which的情况。(1)前有序数词修饰时。This is the tenth gift that I received for
my birthday.这是我收到的第十个生日礼物。(2)前有形容词最高级修饰时。That is the most exciting game that I
have ever watched.那是我曾经看过最令人兴奋的比赛。(3)先行词是all, little, few, something, anything,
everything等不定代词时。All that he told me is true. 他告诉我的一切是真实的。(4)先行词被the only修饰时。The
only thing that I can get is a pen. 我唯一能得到的东西就是一支钢笔。(5)先行词既指人，又指物时。We talked
about the people and the things that we were interested in.我们谈论了我们感兴趣的人和事。
3. 只用which，不用that的情况。(1)定语从句是物时，定语从句由"介词+关系代词which"引导。The thing about which
the teacher is talking is very important.老师正在谈论的那件事非常重要。(2)先行词本身是that,
those时What’s that which is flying in the sky? 在天空中飞的那是什么?
