高中名词性从句知识点

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名词从句
名词从句分为主语从句、表语从句、宾语从句、同位语从句。以此举例：
It is clear that he has gone.
The question is when I can leave.
I don’t know who he is.
The news that he will come late upsets all of us.
一、主语从句优你课教育
1、由连词that, whether引导的主语从句
It is certain that he will come.
Whether he will come is doubtful.
注：whether引导主语从句，不能用if代替
由that引导的主语从句还能改写成由it做形式主语的从句：
It is true that the earth is round.
这类结构一般有：优你课教育
①It +be +形容词+that，这类形容词有clear, obvious, likely, true, probable, possible
②It +be + saidbelievedreportedhopedannouncedknown that…
③It +seemshappensappears that
④It +be +名词+ that从句
It is accepted belief that wind is air in movement.普遍认为风是流动的空气
2、由连接代词（who，which）和连接副 词（when，where，how，why）引导的主语从
句，也可以用it做形式主语引导
Who let out the news remained unknown. =It remained unknown who let out the news.
3、由关系代词what, whatever, whoever等引导的主语从句，此类主语从句不能用形式主
语it引导，合成词在句子中担任成分
What he said at the meeting is important.—主语从句
The thing that he said at the meeting is important.—定语从句
what =the thing that, whoever=any one who, whichever= anything that,但是等号后面
的不能引导名词性从句优你课教育
（误）No matter who gives us help is welcome.
（正）Whoever gives us help is welcome.
（误）I’ll believe no matter what he says.
（正）I’ll believe whatever he says.
二、表语从句
用于表语从句的连词有that, whether, what, whatever, who, whoever, when, where, why,
how等优你课教育
例：The question is how we can get there.
1、that引导的表语从句
①名词主语+ be+ that 从句
常用作主语的名词表示事实、真理或看法、观点：fact, truth, idea, opinion, belief, view, feeling,
suggestion, plan
②wh-引导的主语从句+ be+ that从句
What surprised me most was that all the pupils were unusually quiet.
2、wh-疑问词引导的表语从句
①ThisThat +be+ wh- 疑问词引导的从句
This is how you make the Italian pizza.
②名词主语+ be+wh-疑问词引导的从句优你课教育
The problem is how scientists can keep in touch with the divers under the sea.
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注：if不能用来引导表语从句优你课教育
3、as ifas though, because引导的表语从句
1）as ifas though可以用陈述语气，也可以用虚拟语气
It looks as if it is going to rain.
The patient looked as if he had been ill for a long time.
2）because引导表语从句，主句主语 不能用reason（reason与because不见面）
It may be because I didn’t have a good sleep last night.
The reason why she called me is that she will not attend the party.
如果主句主语是reason，表语从句连接词用that
三、宾语从句
1、连词与主语从句和表语从句一样，但是它与主语从句、表语从句的区别是：
if可以用于宾语从句中，有时可以和whether互换
that在宾语从句中可以省略， 主语从句和表语从句中不能省略，that引导的宾语从句常用形
式宾语it来引导优你课教育
2、介词宾语从句
1）that引导的从句做介词宾语从句优你课教育
that引导的从句很少做介词的宾语从句，只在except, in, but, besides等少数介词后使用
（in that因为…，except that除了…，but that要不是…，除了）
I could say nothing but that I was sorry.
但可跟在带有形式宾语it之后作介词的真正宾语，这类词有see to负责，depend on依靠，
rely on依靠，count on指望
例：See to it that the door is safely locked before you go.你走之前一定要锁好门
2）关系代词副词引导的从句做介词宾语从句
He was satisfied with what I did.
What we should take with us depend on where we’ll stay.
3）不及物动词后跟介词宾语从句
有些不及物动词后边如果跟宾语从句，省去介词
例：I don’t care whether he likes me or not. 比较：I don’t care about him.
I insist that you should learn a second language.
比较：I insist on your learning a second language.
3、宾语从句中需要注意的事项
1）宾语从句时态优你课教育
当主句是现在的时态 （一般现在时，现在进行时，现在完成时），从句时态可根据实际情况
而定。
当主句是过去的时态（一般过去时，过去进行时），从句的时态要变为相应过去的时态
2）主句是I don’t think…宾语从句
主语必须是第一人称Iwe，才能用这样的句型（否定主句，不否定从句）
类似I don’t think…句型的有：I don’t imagine, I don’t believe, I don’t suppose
★注意该句型反意疑问句用法：I don’t think you can do that, can you?
3）连词that省略优你课教育
对于连接词and或but所连接的两个做宾语的that从句中，第一个宾语从句中的that可以
省 略，第二个则不能省略
He said (that) he has worked for nearly ten years here and that he wanted to go home.
4）doubtsure引导的宾语从句，用whetherif和that的区别
★句型：I doubt whetherif…我怀疑……是否……；I don’t doubt that…我毫不怀疑……
I doubt whether he can speak English. 对比：I don’t doubt that he can speak English.
★句型：I’m not sure whetherif…我不确定……是否……；I’m sure that…我相信……
I’m not sure whetherif the news is true. 对比：I’m sure that he can do it well.
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有两种句型：
① be+形容词+that从句
We are certain that we will do well in English writing.
② be+ not+形容词+wh-从句
He is not sure why so many girls want to be air hostesses.
此类形容词有：certain, afraid, sure, anxious, worried, surprised, happy, disappointed.
四、同位语从句
与先行词同位或同等的从句称为同位语从句，一般由连词that引导，在从 句中不担任成分，
不能省略，whether也能引导同位语从句
同位语从句一般有两种：
1、名词+ that引导的从句。常用的同位名词有：answer, belief, doubt, fact, hope, idea, news,
order, question, reply, rumo(u)r, thought等
例：The rumor that there’ll be the earthquake soon spread all over the area.
2、名词+ wh-疑问词how引导的同位语从句
Have you any idea where they are having a rehearsal?
★注：同位语从句与定语从句的区别
同位语that起连接作用，不 充当从句的任何成分，定语从句的关系代词充当从句的某一成分。
对比：I believed the fact that he was honest.
I believed the fact that he thought to be true.
五、名词从句中注意的事项
1、连词that用法总结优你课教育
that引导主语从句、宾语从句通常用it做形式主 语或形式宾语；that在引导宾语从句时可以
省略，引导其他从句不能省略
2、总结whether和if引导名词从句优你课教育
whether可以用于所有的名词从句，if只用于宾语从句
1、在宾语从句中，whether后面可直接跟or not，而if不能
I don’t know whetherif I can come or not.
比较：I don’t know whether or not I can come.
2、如果宾语从句是否定结构，只能用if，而不能用whether
I don’t care if he doesn’t show up. 优你课教育
3、介词宾语从句只能用whether引导
We worried about whether he was in good health.
4、引导主语从句、表语从句、同位语从句时用whether
The question whether he should come himself or send another one hasn’t been decided.
5、whether后可接动词不定式，而if不可以。 如果用形式主语的时候，whether和if都可以。
It’s not clear to me whetherif she likes the present.
6、whether引导的宾语从句放句首，不能用if代替优你课教育
Whether he is an expert, I don’t mind.
7、discuss后的宾语从句用whether
We are discussing whether we should go swimming.
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