定语从句1、功能：=形容词，修饰名词或代词，在句中作定语一：先行词：被定语从句所修饰的词二：关系词：用来连接定语从句，并在从句中代表先行词。
在从句中充当的成分：主语、宾语学会找关系词，看先行词指的是什么-----先行词，看关系词在从句中所充当的成分。
2、一般用法先行词是物：which that先行词是人：who whom that关系代词在从句中作宾语时可以省略。
e.g. The young man ( whom ) you saw was our manager.There is something ( that ) we must keep in mind.限制性定语从句与非限制性定语从句（逗号隔开非限制）1)限制性定语从句：从句与主句关系密切，去掉从句，主句意义不完整，甚至不合逻辑。
e.g. I was the only person in our office who was invited.（去掉定语从句，意思就不完整）2)非限制性定语从句：从句对先行词关系不密切，去掉定从句，意思仍然完整。
形式上用逗号隔开，不能that用引导。
e.g. Tom’s father, who is over sixty, still works hard day and night.that与which的区别1）用that而不用which的情况；②先行词有最高级修饰，有序数词修饰；①先行词为不定代词all, anything, nothing, …③先行词有only, very, any等词修饰；④先行词既有人又有物时。
2）用which而不用that的情况：①引导非限制性定语从句；②指代前面整个主句的意思；③介词+ 关系代词。
3、whose的用法关系代词与其后的名词构成所有格，即“的”时，它既可以修饰指人的先行词，也可以修饰指物的先行词。
e.g. 1. The girl is my daughter. Her work got the first prize.The girl whose work got the first prize is my daughter.4、介宾结构关系代词在从句中作介词的宾语时，介词可以提前，但关系代词只能用which（物）或whom（人）。
e.g. 1. The man is a famous runner. You talked to him just now.The man to whom you talk just now is a famous runner.2. The chair is made of wood. He is sitting on it now.The chair on which he is sitting now is made of wood.3. He is a library assistant. I borrowed some books from him.He is a library assistant from whom I borrowed some books.4. It is a famous school. He graduated from it 3 years ago.It is a famous school from which He graduated 3 years ago.有一些动词短语中的介词是固定搭配，不可以拆开。
(look after take care of look for)e.g. He is the student who the teachers are looking for.The number of the children who she takes care of is 30.5、关系副词：when where why = 介词+which先行词：时间——>when = on which 从句：时间状语地点——>where = in/at which 地点状语原因——>why = for which 原因状语判断把先行词放回从句中（关系词）作什么成分：作状语用when where和why，否则用前面所述。
e.g. 1. I will never forget the day./ I went to university on that day.I will never forget the day when/ on which I went to university.2.This is the house. / He used to live in the house.This is the house where/ in which he used to live.3.I don’t know the reason. / He did it for this reason.why/ for which he did it.I don’t know the reason①一般用法1.Tomis good at maths,so I think he is the student______can help you to work out this problem. A．whom B．who C．which D．whatnot sure whether this is the book________my brother read the year before last.2.I’ｍA．whose B．as C．what D．which3.This is the factory________we visited the other day.A．where B．in which C．there D．/②that/which4.Anything________could be found has been used to repair the damaged bridge.A．which B．that C．what D．how5.The most important thing_______we should pay attention to is the first thing______I have said. A．which；that B．that；which C．which；which D．that；that6.Some great people said it was their primary school teachers and their lessons________theywere fond of________influenced their whole lives.A．which；that B．that；which C．which；which D．that；that7.Carol said the work would be done by October，________personally I doubt very much.A．it B．that C．when D．which8.He told us the stories and the writers ________interested him.A．that B．which C．what D．who9.Those________want to see the film please write down your names here.A．them B．what C．whose D．who③关系副词10.We are living in an age________everything is changing rapidly.A．which B．that C．in that D．when11.May the fourth is the day________we Chinese people will never forget.A．which B．when C．on which D．about which12.There are several research centers in China__a certain disease called Bird Flu is being studied.A．which B．where C．when D．what13. After living in Paris for fifty years he returned to the small town________he grew up as a child.A．which B．where C．that D．when14. There are many things in different areas____we can do to reduce the possible dangers of AIDS.A．where B．there C．what D．that15. Do you still remember the day________we first met?A．that B．when C．what D．on that16*. The noise from the karaoke hall is coming to a point________we can’t put up with it . A．that B．where C．when D．why17.The reason________I’m writing to you is to tell you about a party on Saturday.A．because B．why C．how D．which④介宾18. The engineer________my father works is about 60 years old.A．to whom B．on whom C．with which D．with whom19. He is a man of great experience，________ much can be learned.A．who B．that C．from which D．from whom20.The English play________my students acted at the New Year’s party was a great success. A．for which B．at which C．in which D．on which⑤whose21. This is the boy without________help I couldn’t have passed that difficult exam.A．who B．whom C．whose D．that22.Look out！Don’t get too close to the house________roof is under repair.A．whose B．which C．of which D．that。