一、先行词和关系词
1）Whoever spits in public will be punished here.（“Whoever”可以用“anyone who”代替）
2）The parents will use what they have to send their son to technical school. （“what”可以用“all that”代替）
但这两句句子已经不是定语从句了，是名词性从句。因为定语从句一定要有先行词，而名词性从句没有。将“Whoever”、“what”分别用“Anyone who”、“all that”代替后，才是定语从句，先行词分别是“Anyone”、“all”。
An invitation from her boss, ___came as a surprise.
A. it B. that C. which D. he
答案C。
a选项it，使前后成为两个句子，中间无连词连接，语法错误；b项that，此为非限定性从句，不能用“that”修饰；c选项which，which在从句中做主语，用来代指前面的这件事；d选项he；前半句中是her boss，所以不正确。
2）The weather turned out to be very good, ___ was more than we could expect.
A. what B. which C. that D. it
答案B
A选项不能用来引导定语从句，C选项只能引导限定性定语从句，而D选项习惯上并不适用。
3）It rained hard yesterday, ____ prevented me from going to the park.
A. that B. which C. as D. it
答案B
“as”和“which”在引导非限宾语。但不同之处主要有两点：
（1）importance to me, as my own is.
在一定的语言环境里，有些名词可以具有形容词的性质。这些名词主要是那些表示人的身份、职业、状态的名词。值得一提的是，在这些具有形容词性质的名词之后，引导定语从句的关系代词不能用“who / whom”。
（2）动词短语先行成分。
这种动词短语既可是限定形式也可是非限定形式。如果是动态动词短语，它们在从句中就一般有限定或非限定形式的替代动词“do”和“as / which”一起代替。“do”可以出现，也可以不出现，但不能用其它动词代替。
（3）句子作先行成分。
这句子可以是整个主句也可以只是主句中的一个从句。有时是连续几个句子，有时甚至可以是一个完整的故事。
二、“as/which”特殊定语从句在句中的位置。
由于先行成分的构成成分”特殊定语从句在句中的位置有以下几种情况：
1. 形容词作先行成分时：形容词的“which”特殊定语从句置于先行成分之后。
2. 动词短语作先行成分时，“as / which”特殊定语从句置于先行成分之后。但是，当从句中含有表示主观意志的插入成分时，“as”特殊。
3. 句子作先行成分时：“as”特殊定语从句的位置较灵活，可以置于先行成分之前、之中或之后。但如果先行成分是直接引语，“as”特殊定语从句与否定词的相对中则常用一些表示“合乎自然规律”、“众所周知”或“经常发生”等意义的词语，如natural, known to all, usual等。
4. 有无状语意要是方式状语意义，而“which”特殊定语从句则无状语意义。“as”特殊定四、关系代词“as”与“which”一词。如：
Freddie, as might be expected, was attending the conference.
1). “Which”作主语时，谓语动词不限，主动被动皆可，只是谓语动词为被动语态时助动词“be”省略。
2). “as”和“which”都可以在特殊定语从句中宾语。
3). “as”和“which”在特殊从句中作补语。如：
We thought him a gentleman, as/which he could never be.
“as”特殊定语从句中可以主谓倒装，“which”从句中则不能主谓倒装。
如果先行成分不是主语补语或宾语补语，关系代词用“which”而不用“as”。如：
He talked like a native, which/as he hardly was.
5.as用法：
1).as引导限制性定语从句
a.such....as
He is not such a fool as he looks.
I have never heard such a story as he tells.
b.the same ....as
This is the same book as I lost last week.
(区分the same...as与the same....that：两者都引导定语从句。that从句中说明的名词与the same修饰的名词是同一个。as从句中说明的名词与the same修饰的名词是同一类，而非同一个。举例：①This is the same pen that I lost. 这支钢笔就是我丢的那一支。②This is the same pen as I lost. 这支钢笔跟我丢的那支笔一模一样。)
c.as...as
As many children as came were given some cakes.
2).as引导非限制性定语从句
常用句式:as is said above 综上所述
as is known to all 众所周知
as is often the case 通常如此
as is reported in the newspaper 如报纸所报道的
6. “which”在特殊从定法
（1）不用that的情况
（a）在引导非限定性定语从句时。
（c）The tree, which is four hundred years old, is very famous here.
（b）介词后能用。
We depend on the land from which we get our food.
We depend on the land that/which we get our food from.
（2）只能用“that”引导：如先行词被“last,just”修饰时，只用“that”。
（d）先行词为序数词、数容词，又有人和物时。
（f）先行词指物，在主句中作是“the way”或“the reason”时，“that”可作关系副词，也可省略。
（h）主句的主语是疑问词“who /which”时，避免重复要用“that”．
举例：
Is this the book that you borrowed in the library?
这是你在图书馆借的书吗？
Who that break the window should be punished．
谁打碎了窗户谁该受罚。
All that needed is a supply of oil.
所需的是石油供应。
The thief gave out everything that he had stolen to the police.
那贼最终把偷的全部东西交给了警察。
定语从句只能“that”引导的情况：
1、先行词是最高级或被最高级修饰。
This is the most interesting book that l have ever read.
2、先行词是序数词或被序数词修饰。
The second foreign country that l expect to visit is Greek.
3、先行词是不定代词时，如all、few、little、much、anything、nothing、something
This is the very good dictionary that I want to buy.
4.、先行词既有人又有物时
Can you remember the scientist and his theory that we have learned?
5、先行词被“only”、“the every”、“no”、“one of”、“the right、“the same等修饰
He is the only person that l want to talk to.
6、在以“which”、“who”、“whom” 引起的问句中，为避免重复，常用that
Who is the man that is standing there? Which is the T-shirt that fits me most?
7、“there be”句型中
8、先行词在主句中作表语，或者关系代词本身作从句的表语时宜用“that”
“that”在作宾语时可省略。
（五）区分定语从句和同位语从句
1、定语从句修饰先行词，它和先行词是修饰关系；
同位语从句说明先行词的具体内容，是补充说明的关系。
（1）The boy who is playing football is my classmate.（定语从句）
2、定语从句由关系代for advice.
（3）The fact that the moon moves around the earth is known to all.
（4）The fact is that the moon moves around the earth.(这是一个表语从句！）
(六)特殊的定语从句
1)but也可用作关系代词来引导定语从句，意思接近于that(who).....not(这种用法已经有些陈旧）
There is no tree but bears some fruit.没有不结果实的树。
There are very few but admire his talents.很少有人不佩服他的才华。
Surely there isn't a mother but faces this problem.可以肯定，凡是母亲都面临着这个问题。
2）whereby,wherein,whereupon也可以引导定语从句，相当于by which,in which,upon/on which.这种用法已经有些陈旧，且仅用于书面语。
[定语从句]介词+关系词
1）介词后面的关系副词不能省略。
2）“that”前不能有介词。
3）某些在从句中充当时间，地点或原因状语的介词+关系词结构可以同关系副词“when”和“where”互换。例如：
This is the house in which I lived two years ago. 这是我两年前住过的房子。
This is the house where I lived two years ago.
Do you remember the day on which you joined our club？ 还记得你加入我们俱乐部的那一天吗？
Do you remember the day when you joined our club？
二、介词与关系代词
“介词+关系代词”的结构
1. “介词+ which”在关系分句中分别可作时间、地点和原因状语，代替相应的关系副词when, where和why。如： ①I still remember the day on which (= when) I first came to school. 我仍然记得初来学校的那一天。 ②The factory in which (= where) I work is a large one. 我工作的工厂是一个大厂子。 2. “介词+ which（指物）/whom（指人）”在关系分句中作地点状语，表示存在关系，关系分句主谓常须倒装。如： ①They arrived at a farm house, in front of which sat a small boy. 他们来到一处农舍，前边坐着一个小男孩。 ②I saw a man, on the head of whom stood a bird. 我看见一个人，他的头上有一只鸟。 3. “不定代词或数词+ of + which（指物）/whom（指人）”在关系分句中作主语，说明整体中的一部分。如： ①China has a lot of islands, one of which is Diaoyu. 中国有许多岛屿，其中之一是钓鱼岛。 ②There are a lot of students here, none of whom like the film. 这里有许多学生，他们之中无人喜欢这部电影。 4. “介词+ which（指物）/whom（指人）”在关系分句中作目的、方式或地点状语。如： ①Could you tell me for whom you’ve bought this coat? 你能告诉我这件衣服是给谁买的吗？ ②The man, from whom I learned the news, is an engineer. 这人是一位工程师，我是从他那里得到这个消息的。 5. “介词+ which（指物）/whom（指人）”用于被动结构的关系分句中，作状语，说明动作的执行者。如： ①The wolf by which the sheep was killed was shot. 伤害羊的那只狼被打死了。 ②The man by whom the wolf was shot was a good hunter. 打死狼的那人是一个好猎手。 6. “名词+ of which”代替“whose +名词”在关系分句中作定语。如： ①I saw some trees, the leaves of which (= whose leaves ) were black with disease. 我看见一些树，它们的叶子因害病而发黑。 ②He mentioned a book, the title of which (= whose title) I’ve forgotten. 他提到一本书，书名我忘了。 7. “介词+ which（指物）/whose（指人）”修饰后边的名词。如： ①It rained all night and all day, during which time the ship broke into pieces. 雨下了一天一夜，就在这期间轮船撞碎了。 ②The driver was the man from whose room she had stolen the maps. 司机就是那个男人，她从他的房间偷走地图。 8. “介词+ which +不定式”。此种用法多见于正文体中，相当于一个带有主语和谓语的定语从句。如： She had only 1.87 with which to buy (= she could buy) Jim, her husband, a present. 她只有一元八角七分钱，用这些钱她给丈夫吉姆买一件礼物。分句中分别可作时间、地点和原因状语，代替相应的关系副词when, where和why。如： ①The factory in which (= where) I work is a large one. 我工作的工厂是一个大厂子。
②This is the reason for which (= why )he was put in prison. 这就是他为什么被关起来的原因。
三、介词的正确选择
1. 根据后面动词和介词的搭配关系选择。如： ①This is not the book of which the teacher spoke in class. (speak of 意为“谈论”，相当于talk about) ②The two things of which they felt proud were Jim’s gold watch and Della’s hair. (be / feel proud of 为固定短语，意为“以……自豪”。) 2. 根据前面的名词的搭配关系选择。如： ①I’ll never forget the day on which I first met him. (表示具体的某一天，介词用on) ②The boy pointed to the direction in which he would run. （“朝……方向”，介词用in） 3. 有时需同时考虑动词和介词的搭配关系及介词和名词的搭配关系。如： The clever boy made a hole in the wall, through which he could see what was happening inside the house.
三、介词和关系代词
1）介词后面的关系代词不能省略。
2）“that”前“Do you”作介词的宾语，且可以省略。
例如：（1）The school（that/which）he once studied in is very famous.
“that/which”可以省略。= The school in which he once studied is very famous.“which”不可省略。
（2） 含有介词的短语动词一般不拆开，介词仍放在短语动词的后面。如：look for, look after, take care of等。T This is the watch which/that I am looking for.（T=正确）F This is the watch for which I am looking.（F=错误）
2. 若介词放在关系代词前，关系代词指人时用“whom”，不可用“who”或者“that”；指物时用“which”，不能用“that”；关系代词是所有格时用“whose”
（1）The man with whom you talked is my friend.（T）The man famous.
（2）I bought many books yesterday, three of which are written by Lu Xun.
四、关系代词关系代词（一般情况下）“that”可用在从句做主语，谓动词的宾语，但是不能做介词的宾语。“which”指物，在从句中作主语；“whom”在从句中作宾语；“why”在从句中修语，先行词通常是“the reason”；有时“why”也可用“for+which”代替。
例：A doctor who looks after people's health.主语 谓语 先行词 定语从句修饰先行词五、判断介词和关系代词方法一： 用关系代词，还是关系副词完全取决于从句中的谓语动词。不及物动词后面无宾语，就必须要求用关系副词或者是介词加关系代词；而及物动词后接宾语，则要求用关系代词。
例如： This is the mountain village where I stayed last year.
判断改错:（错） This is the mountain village where I visited last year.
（错） I will never forget the days when I spent in the countryside.
（对） This is the mountain village (which) I visited last year.
（对） I'll never forget the days (which) I spent in the countryside.
例. Is this the museum ____ the exhibition was held?A. where B. that C. on which D. the one,解析： 主、谓、宾俱全，从句部分为句子的状语表地点，既可用副词where，又因 in the museum词组，可用介词in + which 引导地点状语。而此题中，介词on 用的不对，所以选A。
关系词的选择依据在从句中所做的成分，先行词在从句中做主、宾语时，选择关系代词（who, whom, that, which, whose）； 先行词在从句中做状语时，应选择关系副词（“where”地点状语，“when”时间状语，“why”原因状语）。
