高三语法专题名词性从句
主语从句，表语从句，宾语从句和同位语从句在复合句中的作用相当于名词，因此这四种从句统称为名词性从句。
一：名词性从句的引导词
1;连接词:that, if, whether.只起引导作用，在句中不充当任何成分．其中that不翻译出来，没有任何含义；而if和whether翻译成”是否”。Eg: That this has happened is not uncertain.
We cannot be sure whether /if our dreams will come true.
2:连接代词：who, , whose, which, what, whatever, whoever, whichever.在句中要充当主语，宾语，表语．I wonder what you are thinking about.
Can you imagine what will happen next?
My hometown is not what it used to be.
３；连接副词：where, when, how, why, how soon, how often, how long, how much.在句中充当相应的状语．
When he will hold the meeting has been decided.
This is how Henry solved the problem.
二：名词性从句的分类与引导词
一）：主语从句
主语从句在复合句中作主句的主语，引导主语从句的词有，that, whether, who, what, which, whoever, whichever, whatever, when, where, how, why等。
Whether we will succeed is still a question.
Whoever comes to the party will receive a present.
注：1. 主语从句的主谓一致
1).主语从句通常被看作一个整体,主句的谓语动词用单数形式.
That they will come is certain
2).由who, whoever引导的主语从句的单复数要视从句中的单复数而定. Whoever say that are to be punished.
Who he is doesn’t concern me.
3).What 引导主语从句时,主句谓语动词的单复数由表语的单复数决定.What he wants are these books.
What he wants is some water
2. 有时为了平衡句式，常用it 做形式主语，而把从句放在后面．
It is a pity that she has made such a mistake.
It depends on the climate whether they are going shopping today.
It is believed that he is a talent
二）.宾语从句
宾语从句在复合句中作主句的宾语，引导宾语从句的词有，that, whether, who, what, which, whoever, whichever, whatever, when, where, how, why等。宾语从句一般放在动词，形容词或介词后。
She has told us (that) she will give us a hand.
He asked me how I was getting along with my new classmates.
I’m afraid that I have made a mistake.
I was interested in what he was doing.
注：1. 有时要用it 作形式宾语，而把宾语从句放在句子的后面。
He has made it clear that he will not give in.
You may depend on it that they are valuable.
2. 如do you think/believe/suppose/expect/imagine后接特殊疑问词引导的宾语从句，疑问词要放在居首。
What do you think is going on outside?
When do you believe he will held the meeting
3. I/We (don’t) think/believe/suppose/expect/imagine后接宾语从句时，反义疑问句要与从句中的主语和谓语保持一致。
I don’t suppose he cares, does he?
4. that引导，通常that可以省略（但that引导其他名词性从句时不可省略）
She has told us (that) she will give us a hand.
三）.表语从句
表语从句在复合句中作主句的表语，引导表语从句的词有，that, whether, who, what, which, whoever, whichever, whatever, when, where, how, because等。表语从句一般放在系动词后。The reason is that I’v e been too busy these days.
That is where he spent his childhood.
The coat is where you left it.
三）.同位语从句的概念
在复合句中用作同位语的从句叫做同位语从句。它一般跟在某些名词后，用以说明该名词表示的具体内容。引导同位语从句的词有，that, whether, who, what, which, when, where, how, why等.常放在fact, news, idea, truth, hope, problem, information suggestion, possibility 等名词后面，用以说明该名词的具体内容。
I heard the news that our team had won.
We haven’t settled the question where we will spend our holidays.
The question who should do the work requires consideration .
2.有时用namely（即），that is to say（也就是说），that is （那就是）等引出同位语或同位语从句。
There is only one way of improving your English , that is , to practice more.
He told us the good news, namely, the museum is open to all.
三：名词性从句的难点和考点
1.语序问题。名词性从句要用陈述语序
The photographs will show you what our village looks like
You can hardly imagine how excited he was when he heard the news
2：引导词that和what的区别
What在从句中要充当主语，宾语或表语，这时what相当于all that/everything that等常译作“所…..的（东西，事情，话等）”。而that只起连接作用，本身无实际意义，在从句中不充当任何成分，that引导主语从句放在居首时不能省略。
What I can’t understand is why he has changed his mind.
That the earth is round is known to us all.
2.引导词if 和whether的区别
if 和whether引导动词后的宾语从句时可以通用，但介词后的宾语从句，主语从句，表语从句和同位语从句不能用if引导。
I don’t care if/whether he will come to my party.
I worry about whether I hurt her feelings.
