二．定语从句
在复合句中,修饰某一名词或代词的从句,称为定语从句,也叫形容词性从句.被从句所修饰的词叫先行词.
eg: a beautiful pig
This is a pig that can sing.
定语从句分为两种：限定性定语从句或非限定性定语从句
注：经典语法中把两种从句的区别说的很多,但高考考题中这方面体现的不多,同学们只需要知道有逗号的是非限,非限中不能用that
eg: He is the person who I am looking forward to seeing.
They discussed a question yesterday, which was very importance.
引导定语从句的关系词有两种：关系代词（that, who, whom, whose, which,as）,关系副词（when, where, why）
1.that
即可以指人,又可以指物,不能用于非限或作介词宾语
eg: This is the box that I lost yesterday.
She is the girl that I like.
2.who
只修饰人.其中who 即可以修饰主语,也可以修饰宾语,whom只能修饰宾语
注：这里所说的主语或宾语是指在从句中所充当的成分
eg: She is the girl who likes you.
She is the girl who/whom you like.
3.which
只修饰物,也可以整句内容.
eg: She heard a terrible noise, which brought her heart to her mouth.
Tom failed in the exam, which made his father angry.
注：先行词是物,用that 不用which的情况
(1)先行词是不定代词all, none, one, any, few, everything等时.但something都可以.
(2)先行词被序数词或最高级修饰时
(3)先行词包括人和物两方面
eg: They talked about the things and the persons that they remembered in the school.
注：先行词是物,用which不用that的情况
(1)引导非限时,先行词可以是词或句子,不用that.
(2)作介词宾语时
eg: He built a telescope thought which he could study the skies.
4.as
常用于 such…as, the same…as, as…as等结构中.还可以译为“正如”,即可放句首或句末,而且常用逗号与主句隔开.
eg: This is not such a book as I expected.
As is known to all, the earth travels around the sun.
注：the same as 与the same that的区别
eg: This is the same tool as I used that time.这和我上次用的工具一样（是同类）
This is the same tool that I used that time.这和我上次用的是同一把工具（是同一个）
注：as与which的关系
（1）相同点：都能引导非限,先行词可以是整个句子,都可以在从句中作主语,宾语或表语
（2）不同点：
①as引导的从句可位于句首或句末,并有逗号和句子隔开.而which引导的从句,只能放在主句后面.
eg: As everybody can see, this elephant is like a snake.
=This elephant is like a snake, as everybody can see.
②as有“正如”的意义,which没有.此条也是高考重点.
eg: As Engels ppinted out, labour created man himself.
注：定语从句和同位从句的区别
比较下列两个句子
(1).We expressed the hope (that) they had expressed.
(2).We expressed the hope that they would come to visit China again.
a.从语法角度上看,引导同位从句的that是连词,只起连接作用,在从句并不做任何成分,而引导定语从句的that是关系代词,除了起连接作用外,还在从句中充当句子成分
b.从语意的角度上看,同位语从句与它前面的名词是同位关系,表示其具体的内容,而定语从句与它前面的名词是所属关系,起修饰作用
再比较下面两个句子
(1).Have you heard the news that a war has broken out in the Middle East?
(2).Have you heard the news that I just told you?
c.同位从句的that一般不省略,而定语从句中的that如果作宾语则可以省略
5.whose
即可以指人,也可指物,表示所属关系
eg: Everyone here will help the girl whose father died in the accident.
He bought a big house whose windows are very beautiful.
6.关系副词where ,when ,why
where表示时间, when表示地点, why表示原因,他们在从句中分别作地点状语,时间状语和原因状语.
当先行词虽然表示时间,地点或原因,而关系词在从句中作主语或宾语而不是状语时,要选用that或which,因此解决此类问题时,分析先行词在从句中作什么成分显得十分关键.
eg: I’ll never forget the day when I first came to Shenyang.
I’ll never forget the day that/which we spent together.
The reason which/that he gave isn’t believable.
The reason why he didn’t come to school yesterday is that he was ill.
解决此类问题我们所采用步骤如下：1,找先行词.2,分析先行词在从句中作什么成分.3,如果作状语,选关系副词,如果作主语或宾语,选关系代词
7. 介词+关系代词 结构
先看下面的例子：
eg: Shenyang is the city where I live.
Shenyang is the city that/which I live in.
Shenyang is the city in which I live.
最后一句话就是我们所说的结构,这一结构在高考中出现的几率十分高,解决此类题我们采用以下步骤.
1．找先行词.2,把先词换到关系代词的位置.3,将句子还原.下面举例说明
例：She is the girl ____ you’re waiting.
A. to whom B. for whom C. in whom D. of whom
通常此类问题都转化为选介词的问题了.找到先行词girl,再将放到whom的位置,将句子还原是：
You’re waiting ____ for the girl.所以,显然选B.
上题可以看出这个介词是由wait这个动词所带来的,但是实际情况要复杂很多.
注：介词+关系代词 结构里介词的选法
(1)根据与前面句词的关系
eg: I can never forget the day____ which I first met her.
(2)根据与后面动词的关系
(3)综合考虑全句内容
eg: He made a hole in the wall ____ which he could see what was happening in the next room.
注：关于引导主语从句时what的用法.
what引导的句词性从句,有时可以不译出来,因为没有准确的汉语意义和它相吻合,但它在从句中充当的成分决定了它独一无二的位置.
我们以下面的例子来感觉一下.
eg: China is no longer what it used to be
China is no longer the country that/which it used to be.
我们有下面两种方式去理解它与定语从句的关系.what一词在句中即起到了先行词又起到了连接词的作用,即双从身分.这是一,还有就是上一句话如果没有what,那么从句中就没有了表语,即真正缺少句子成分.所以,考场同学们一定要仔细分析句子的特点再作结论.
三,强调句型
因为强调句型经常会和名词性从句和定语从句相混淆,所以放在此句讲解
固定结构：
It is/was + 被强调部分 + that/who + 从句
在强调人时用who,其它情况一律用that
eg: It was Tom who helped me .
It was in the park that they caught the thief.
注：由于强调句型的特殊格式,考试时同学们如果看见考题的前两个人词是 it is/was时就要首先考虑是不是强调句型.具体判断方法如下
eg: It was these poisonous products ____ could cause the disease, like flu.
A. that B. which C. why D. when
看到题目前两个单词,先考是不是强调句型.然后把it was 和要填入的空划掉,看所剩的部分是不是完整的句子,如果是,就是强调句型,否则就不是.
所剩部分为： these poisonous products could cause the disease, like flu 完整,是强调句型,而且强调的是物,所以选A.
再比较下面两个句子
It was the forest ____ we caught the thief.
It was in the forest ____ we caught the thief.