同位语从句，主语从句和表语从句
一、同位语从句
1.同位语：当两个指同一事物的句子成分放在同等位置时，一个句子成分被用来说明或解释另一个句子成分，前者就叫做后者的同位语。这两个句子成分多由名词或代词担任。同位语通常放在其说明的名词或代词之后。
eg:We have two children, a boy and a girl.
eg:We ,the chinese people , are determinded to build China into a powerful an prosperous country.
2.同位语从句：与先行词（名词或代词）同位或等同的从句叫做同位语从句。同位语从句的先行词多为fact, news, idea, opinion, thought, suggestion, promise, word(消息), message, request, order, proposal, plan, question等，多由连接代词that引导。
eg:The fact that the money has gone doesn’t mean it was stolen.
eg:The hope that he may recover is faint.
3.同位语从句的引导词及特点：
1）连接代词that 引导的同位语从句中，that只起连接作用,不充当句子的成分。2）连接代词who, which, what和连接副词where, when, why, how引导的同位语从句中，其引导词在句子中起连接作用即将主句与从句连接起来，且要在从句中充当成分。
3）从属连词whether, if引导同位语从句中，whether, if只起连接作用，不在句子中充当成分，也不替代先行词。
注：连接代词与连接副词，关系代词与关系副词的区别如下：
连接代词和连接副词是引导同位语从句的，其在句子中起连接作用即将主句与从句连接起来，且要在从句中充当成分（that除外）；关系代词与关系副词是引导定语从句的，其在句子中除了具备与连接代词和连接副词同等的作用外，即起连接作用（连接主从句），在句子中充当成分，而且还要替代先行词。
eg:It is a question how he did it.
eg:The question who should do the work requires consideration.
分析：此类连接代词who及连接副词how起连接作用即将主句和从句连接起来，
并且在从句当中充当成分，但是并不替代先行词（定语从句的关系代词和关系副词要替代先行词）。
高考重点：分隔式同位语从句
eg:Word came( that he was killed in the accident.)
实战练习：
1.He made a promise ____he would help me.
A. what
B. when
C. which
D. that
2．I have no idea ____ he will come back.
A. where
B. when
C. what
D. there
3. One of the men held the view ____ the book said was right.
A. what that
B. that what
C. that which
D. which that
4. There’s no possibility ____ Bob will win the first prize in the match will come true.
A. that that
B. there that
C. there whether
D. it whether
5. He can’t answer the question ___ he has money.
A. whenever
B. wherever
C. how
D. why
引导同位语从句的that与引导定语从句的that的区别如下：
1）从语法角度看，引导同位语从句的that，只起连接作用，在从句中并不作任何成分，也没有任何含义，而引导定语从句的that ，除了起连接作用外，还要替代先行词并在从句中充当句子成分。
2）从引导词省略的角度看，同位语从句中的that不能省略，而定语从句中的关系代词that，当其在从句中作宾语时，常常可以省略。
eg:The news (that) he told me just now is true.(定语从句)。
eg:The news that I have taken the first place in English is true.(同位语从句)。
二、主语从句：在复合句中充当主语成分即以从句作主语的句子叫做主语从句，通常有由连接代词that，what，which，whoever，whatever，连接副词when, how, where, why, however，wherever，whether引导。eg:Whatever was said here must keep secret.
注意：这类主语从句可以直接用在句首，也可以放到句尾，前面用it作为形式上
的主语，这两种结构基本上可以换用，意思上没有什么差别：
eg:Whether he will join us won’t make too much difference.
It won’t make too much difference whether he will join us .
注意：1）if引导的主语从句不能位于句首，if也通常不用来引导同位语从句，定语从句及表语从句。
2) that 引导主语从句，表语从句，同位语从句时不能省略，在引导定语从句并在从句中作主语时也不可以省略。
eg:That he was chosen made a hit in his village.
实战练习
1. ____ matters most in learning English is enough practice.
A. what
B. why
C. where
D. which
2. His movie won several awards at the film festival , ____ was beyond his wildest dream.
A. which
B. that
C. where
D. it
3. ____ he refered to in his article was unknown to the general reader.
A. That
B. What
C. Whether
D. Where
4.The book is of great value. ____ can be enjoyed unless you digest it.
A. what
B. which
C. everything
D. nothing
5. It is none of your business ____ other people think about you. Believe in yourself.
A. how
B. what
C. which
D. when
6.____ worries me is the way he keeps changing his mind.
A. This
B. That
C. What
D. It
三、表语从句：在复合句中充当表语成分，通常放在be ,look, seem, appear等连系动词之后，即从句充当句子的表语，通常由从属连词that ,whether, as, as if ，连接代词who,whom, whose, what, which, whoever, whatever,whichever,连接副词where,when, how, why等引导。
eg: The problem is who we can get to replace her.
注意：where, why, because,how等引导的从句作this is 或that is 或it is 的表语。eg: This is why we put off the sports meet.
实战练习
1.The reason why he didn’t come to school today was ____ he had to look after his father at home.
A. why
B. because
C. that
D. what
2. That is ____ I was born and grew up.
A. what
B. where
C. how
D. if
3. I really don’t know ____ a person like him can help me with .
A. which
B. it
C. what
D. that
4. After ____ seemed like hours he came out with a bitter smile.
A. which
B. it
C. what
D. that
5. He didn’t go to school today, it was ___ he was ill.
A. why
B. how
C. because
D. what
预祝同学们金榜题名1-5 D B B A D
1-6 A A B A A C
1-5 C B A C C