定语从句
定语从句在句中做定语，修饰一个名词或代词，有时也可以修饰部分或整个句子。
被修饰的名词，词组或代词即先行词。定语从句通常出现在先行词之后，由关系词（关系代词或关系副词）引出。
关系代词有：who, whom, whose, that, which, as。
关系副词有：when, where, why, how。
关系代词和关系副词放在先行词和定语从句之间，起连接作用，同时又可做定语从句的一个成分。当关系代词做宾语时可以省略。
定语从句中的谓语动词必须在人称上和数量上和先行词保持一致。
定语从句分为限制性定语从句和非限制性定语从句。关系代词和关系副词的作用：
一、关系代词
1. 先行词指物时，关系代
词用that 或which（在句中作主语或宾语）。如：China is a country which / t hat has a large population. The computer game which/ that he is playing is his favo rite.
2.先行词指人时，关系代词用（who）作主语或宾语，whom (作宾语)，whose (作定语)，that (作主语或宾语)。如： The man who is mending the machine has been retired.
This is the policeman who/ whom they were talking about yesterday.
I like the girl whose mother is an actor.
注意：下列情况下关系代词只用that 而不用which 或 who。
1. 先行词是指物的不定代词，如：all, little, few, much, none, a nything, nothing, everything 等时。如：I didn't understand the
words all that he said.
2．先行词由最高级、序数词以及any, very, only, all, no, just 等所修饰。如：This is the most beautiful place that I have been to .
3.先行词既包括人，也包括物。如：They always like to talk about the man and the things that they see on the road. . 4当主句是以which 或who 开头的特殊疑问句时。
如：who is the man that opened up the lab？.
二、关系副词引导的定语从句
关系副词可代替先行词是时间、地点、方式或理由的名词，在从句中作状语。关系副词when, where, why, how的含义相当于"介词+ which"结构，因此常常和"介词+ which"结构交替使用，例如：
I still remember the day when I was invited by the teacher last year.
It is the place that he visited last year.
Beijing is the place where (in which) I was born.
Is this the reason why (for which) he refused our offer? I'm surprised the way how (by which) he works out the problem.
三、例题解析：举一反三，学的更轻松！
1. He is a friend ______ ca n help you in time of need.
A. who he
B. whose
C. /
D. who
解析：引导词在定语从句中做主语，指人。应选D 。
2.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, that
解析：先行词前有序数词，最高级时，引导次只能用 that. 应选D.
3. This is the only one of these books that ______ worth reading.
A．has B. have C. is D. are 解析：引导词that在句中作主语，代指one ，应选C。
4.The man ______ talked t o you just now is my father.
A. who
B. he
C. whi ch
D. whose
解析：引导词在句中作主语指人，应选A.
5.They thought too much about ______.
A. which I had said
B. what I had said
C. that I had said
D. I had said
解析：此题引导词作在从句中作宾语，表示说话的内容，应选B。
练习与巩固：熟能生巧，
取得好成绩！
一、选择最佳答案填空：1．Did you find the notebook ______ Jim had given me for my birthday?
A. who
B. whom
C. which
D. whose
2. That's all ______ I have seen and heard.
A. which
B. that
C. where
D. what
3. Have you seen the man _ _____ plan we were talking about ______ yesterday ?
