如何辨别定语从句的关系词塘桥中学包小波同学们，你们知道以下这些谚语吗？It’s the first step that costs.万事开头难。

Not all that glitters is gold.闪光的未必都是金子。

He who would climb that ladder must begin at the bottom.千里之行，始于足下。

A good book is a best friend who never turns back upon us.好书如挚友，情谊永不变。

在这些句子中，你发现什么共同点了吗？对了，这些句子都运用了定语从句。

定语从句在复合句中的作用相当于形容词，在句中作定语，修饰前面的名词或代词。

斜体加粗的单词都被称为关系词，也叫引导词。

被定语从句修饰的词称为先行词，就是上述谚语中有下划线的单词，定语从句一般放在先行词的后面。

要想掌握定语从句，就必须了解引导定语从句的关系词。

关系词分为关系代词和关系副词。

关系代词有who，whom，whose，that，which和as，关系副词有when，where和why，他们在先行词和定语从句之间起联系作用，同时在意义上代表先行词，并在定语从句中担任某个成分。

我们要辨别定语从句中不同的关系词，必须掌握以下的方法。

一、关系代词的用法1．普通代词与关系代词的区别例如：I have a brother. He likes playing the piano.（合并为一句）I have a brother who/that likes playing the piano.简单句中的普通代词he起了指代前一句中brother的作用，并且是本句的主语，两个句子都是独立的。

而两句合并后，句中的关系代词who/that除了代替先行词brother之外，它还在定语从句中担任了一定的成分，同时连接先行词与它引导的定语从句。

2．who指人,做主语。

例如：The person who is in blue will go to the concert with me tomorrow.本句中的who充当从句中的主语, 划线部分是从句。

当who作为定语从句的关系代词在句中充当主语或宾语时，都可以用that来替代。

3．who/whom指人,做宾语。

例如：The man who/whom I look after is my father.在例句中，who/whom做从句中介词with的宾语，这个句子也可以写成The man with whom I talked is our teacher.如果从句中介词提前，那么就不能用who或that，只能用whom引导从句了。

这个句子还可以写成：The man I talked with is our teacher.在口语及非正式文体中常省略中间的关系代词who。

4．whose多指人，也可指物。

例如：The room whose door is open is mine.This is the boy whose mother is an engineer.第一句中的whose指代的是主句中的room, 第二句中的whose指代的是主句中的boy。

在定语从句中运用whose时，要注意它的后面肯定有名词，因为它本身也是这个名词前的定语，然后跟着的是从句中的谓语和其它成分。

5．which 指物，做主语或宾语。

例如：Two days later Jenny received the present which her friend bought her.I want to buy a book which was written by Mark Twain.which在第一句中充当从句中的宾语，而在第二句中充当从句的主语。

which在句中作宾语时可省略, 如介词提前则不能省。

例如：I went to the library which you borrow books from.= I went to the library you borrow books from.=I went to the library from which you borrow books.6．that 指人/物，做主语或宾语。

例如：Who is the woman that you are waiting for？The train that left just now will go to Paris.★需要注意的是：（1）that作宾语时可以省略，如，The news that John told me is true.=The news John told me is true.（2）介词提前时，不能用that, 指人只能用whom，指物用which。

如，The little girl that I spoke to just now is Henry's sister.= The little girl to whom I spoke just now is Henry's sister.The library that we often borrow books from is on the second floor.= The library from which we often borrow books is on the second floor.（3）有些情况下只用关系词that或省略，而不宜用which。

a).先行词被形容词最高级，序数词或the only, the very, no, the last等修饰时,如，This is the most interesting novel that I have ever read.The first lecture that I will give will be held in the afternoon.b).先行词all, something, nothing, anything，everything, much, little, few, none, the one等时, 如，Here is something that I will tell you.c).先行词既有人也有物时, 如，I can remember the persons and some pictures that I’ve seen.7．as指人或物，在从句中作宾语，有时做主语或表语，常用于“the same＋名词＋as或such＋名词＋as”等结构中及先行词是代词such或same的情况下。

例如：I lived in the same neighbourhood as Mr. Wang lived three years ago.T he King’s Speech is such an interesting film as I thought.二、关系副词的用法关系副词在从句中作状语，其作用相当于介词短语。

1．when表示时间，在从句中通常做时间状语，也可用介词+ which来替换。

例如：Do you remember the time when we first went to Beijing several years ago?That was the very day when I first saw my general manager.= That was the very day on which I first saw my general manager.2．where表示地点，在从句中通常做地点状语，也可用介词+ which来替换。

例如：This is the hotel where they stayed last month.=This is the hotel in which they stayed last month.3．why表示原因，在从句中通常做原因状语，也可用for which来替换。

例如：I don’t know the reason why Mingming is often late for school.=I don’t know the reason for which Mingming is often late for school.★需要同学们注意的是：如果关系词后面是完整的句子，句中已有主语、谓语、宾语三个成分，就不能用that, which, who, 因为他们在定语从句中做主语或宾语，那么就要考虑是不是用when, where 或why来解题。

例如：I shall never forget those years _______ I planted the trees on the farm.A. whereB. thatC. whichD. when本题的从句中主语是I，谓语是planted, 宾语是the trees，地点状语也有了，是on the farm，而且先行词是those years，因此根据从句的句子成分来分析出答案不可能是宾语或是主语，应该是时间状语，选择D。

例如：This is the place _______ the accident happened last night.A. whereB. thatC. whichD. why本题的从句中主语是the accident，谓语是happened, 而且是不及物动词，后面不能跟宾语，而last night是时间状语，而且先行词是the place，所以分析下来是缺少地点状语，因此答案是A。