编者按：定语从句是高中阶段的重点语法，但同学们在运用它的过程中会出现较多的失误，其主要原因在于同学们在学习过程中对一些细节掌握得不够好。本期文章着眼于关系代词和关系副词的选取以及非限制性定语从句的疑难点，以解决同学们在学习定语从句的过程中遇到的实际问题。
定语从句是高中英语的一个常考点。2011年高考对这一知识点进行考查的所有题都是考查对关系词的辨析与选择。同学们经常混淆关系代词that和which，as和which以及who和whom的适用范围。希望本文能帮助同学们掌握这三组常考的关系代词。
一、which和that
1.which和that均可指物，其中that也可指人，在定语从句中充当主语或宾语。具体如下表：
2.宜用that而不宜用which的情况。
（1）先行词为all，everything，nothing，something，anything，little，much等不定代词时。如：
Finally，the thief handed everything that he had stolen to the police.
最后那个小偷把他偷的所有东西都交给了警察。
（2）先行词被all，every，no，some，any，little，much等不定代词修饰时。如：
Please send us any information that you have about the subject.
请将你所有关于那个主题的信息发给我们。
（3）先行词被序数词或最高级修饰时。如：
That’s the most expensive hotel that we’ve ever stayed in.
这是我们住过的最贵的宾馆。
（4）先行词被the only，the very，the same，the last修饰时。如：
This is the very book that I want to find.
这就是我想要找的那本书。
（5）先行词既有人又有物时。如：
They talked for about an hour of things and persons that they remembered in the school.
他们谈论他们记得的在学校的那些人和事，谈了大约一个小时。
（6）先行词是who或which引导的主句时。如：
Which is the car that killed the little girl？
是哪一辆车撞死了那个小女孩？
（7）主句为there be 句型时。如：
There are more than 200，000 people that died or were injured in the earthquake.
那次地震死伤人数超过了20万人。
例1 In this factory I saw little ____ was different from ours.
A. which B. what C. where D. that
解析 答案为D。先行词为little，因此用that，不用which。
例2 Let’s discuss the only question _____ we are interested in.
A. which B. that C. as D. about which
解析 答案为B。先行词被the only修饰，因此用that，不用which。
3.只用which不用that的情况。
（1）关系代词在限制性定语从句中紧跟介词作宾语时。如：
The school in which his mother teaches is in the west of the city.
他母亲任教的那所学校在城市的西边。
（2）从句为非限制性定语从句时，which既可以指代先行词，也可以指代前面整个句子的内容。如：
My watch，which is very old，stopped again.
我的手表很旧了，又停了。
Mary was much kinder to Jack than she was to the others，which，of course，made all the others upset.
玛丽对杰克比对其他人要好，这当然让其他人感到不舒服。
例3 A dictionary is a book _____ one can find out the meaning of words.
A. which B. in that C. in which D. which
解析 答案为C。分析可知，此处需要关系副词，但选项中无关系副词。用“介词+关系代词”代替。that作关系代词时，不能用于介词之后。
例4 Some of the road were flooded，____ made our journey more difficult.
A. which B. it C. what D. that
解析 答案为A。此处关系代词指代前面整个句子，因此只能用which，而不用that。
二、as和which
1.关系代词引导的定语从句位于句首时，一般用as。
As we all know，he studies very hard.
正如我们大家所知，他学习很努力。
2.与such/so/as/the same连用时，一般用as。
The book is written in such easy English as beginners can understand.
这本书很简单，以至于初学英语者都能看懂。
At this time of the day，all buses have to carry as many passengers as they can.
每天的这个时候，所有的公交车都要尽可能多地载客。
3.当从句和主句语义一致时，用as，反之则用which。
She has married again，as was expected.
正如大家预料的那样，她再婚了。
She has married again，which was unexpected.
出乎大家意料的是，她再婚了。
4. as在从句中作主语时，后面常接行为动词的被动语态，如be known， be reported等。如果从句中行为动词是主动语态，一般要用which作主语。
She has been late again，as was expected.
正如大家所料，她又迟到了。
Tom has made great progress，which made us happy.
汤姆取得了很大的进步，这让我们很开心。
例5 I have the same shirt _____ you have.
A. which B. that C. as D. who
解析 答案为C。先行词被the same修饰，因而用as，形成固定搭配the same... as。
三、who和whom
1.who和whom在定语从句中均指代表示人的先行词，who可作主语或宾语，whom只可作宾语。
The man who/whom you met just now is called Jim.
你刚才遇见的那个人名叫吉姆。
Where’s the girl who sells the tickets？
那个卖票的女孩在哪里？
2.介词前置时，介词后作宾语的只能用whom，不能用who。
The brave man，by whom the boar was shot，is a good hunter.
射中野猪的那个勇敢的男人是一个好猎人。
例6 In the dark street，there wasn’t a single person _____ she could turn for help.
A. that B. who C. from who D. to whom
解析 答案为D。此处源于词组turn to sb. for help，因此答案是to whom。
（责任编校/彭益）