定语从句（attributive clauses）
定语从句是修饰名词的从句,起形容词的作用.定语从句一般由一个关系代词或关系副词引导,被修饰的名词称为先行词.定语从句一般要紧接在先行词后面.
定语从句就其与先行词的关系来说,可分为限制性定语从句和非限制性定语从句两种.
1、限制性定语从句限制或规定先行词的范围,和先行词有着不可分割的关系,对于全句的意义此凳遣豢扇鄙俚摹h绻?サ舳ㄓ锎泳洌?涞囊庖寰筒幻魅贰⒉煌暾?that ** the man who g**e us a report yesterday.
那位就是昨天给我们作报告的人.
1）引导限制性定语从句的关系代词有who,whom,whose,that,which.关系代词代表先行词,同时又在从句中担任一种句子成分,如主语、宾语、表语或定语.关系代词的用法见下表：
（1）who代表人,在从句中作主语,如：
he give those books to the students who were interested.
（2）whom也代表人,在从句中作宾语,有时可以省略,如：
many people(whom)we know are sports men.
有时也可以用who来代替whom,例如：
the worker(whom/who)you mentioned has not come.
在介词后,只能用whom,不能省略,如：
the man to whom you spoke just now ** a doctor.
比较下列句子：
the boy about whom you talked has gone home.
the boy(whom)you talked about has gone home.
（3）whose代表“某人或某物的”,在从句中作定语,如：
the woman whose bike was stolen ** john’s mother.
th** ** a pretty flower whose name i don’t know.
（4）which代表物,在从句中可作主语；如：
we often use the ladder which ** made of wood.
也可作宾语,当作宾语时,可以省略；如：
they like the trees(which)they planted.
但是在介词后,which不能省略,比较：
th** ** the book about which i told you last week.
th** ** the book(which)i told you about last week.
（5）that既可代表人,又可代表物,如：
the boys that sends news**s ** my brother.
the method that were taught to john were easy to learn.
that常常可以替代who,whom和which.如：
the man that told you the news will come here th** afternoon.
he ** the man(that)i saw in your room yesterday afternoon.
th** ** the book(that)i like best.
但是,在介词后不能用that；当先行词为 everybody,anybody,anyone等时要用who,不用that;当先行词前有形容词**或all,any,no,only,little,much等词时,或先行词本身为all,little,much,anything,something,nothing等词时,要用 that,不用which.如：
** there anyone who can answer th**question?he ** the tallest man that has ever lived here.
th** ** the best novel that i h**e ever read.
there ** something important that you h**en’t done.
2）引导限制性定语从句的关系副词有where,when.关系副词在从句中作状语,意义上相当于“介词+关系代词”.
（1）where修饰表示地点的名词,在从句中充当地点状语,意义上相当于一个介词加which(on which,in which等),如：
th** ** the place where(=in which)i was born.
the office where(=in which)he works ** on the second floor.
（2）when修饰表示时间的名词,在从句中充当时间状语,意义上相当于一个介词加which(on which,in which等),如：
april ** the month when(=in which)we h**e a lot of rain.
i will never forget the day when(=on which)i met her.
2、非限制性定语从句
非限制性定语从句是对意义明确或者独一无二的人或物作进一步的说明,与先行词只有比较松散的关系,如果去掉定语从句,主句仍然成立.在书面语言中,通常用逗号把从句和主句隔开.例如：
beijing,which ** in the north of china,** the heart of the country.
北京位于华北,是**的心脏.
定语从句
1 that 在从句中作主语或宾语 指物或指人.
2 which 在从句中作主语或宾语 指物.
3 what 不能引导定语从句.
4 that 不能用于引导非限制性定语从句.
就定语从句中挺难区分的.（个人看法）
做选择靠语感.不能死掰.要灵活!是别人的,我用一下,