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名词性从句之主语从句一、名词性从句概述：在句子中起名词作用的各种从句统称为名词性从句。
根据它们在句中的语法作用，这类从句又可分为主语从句、同位语从句、表语从句和宾语从句。
二、主语从句定义：在句中起主语作用的从句称为主语从句。
引导主语从句的连接词主要有：单纯连词(that, whether/ if)、连接代词(what, whatever, who, whoever, whom, whose, which, whichever 等)和连接副词(when, where, why, how, whenever, wherever, however 等)。
1)that引导的主语从句(1)由连词that引导的主语从句:引导词that无含义/在句中不做成分/不可以省。
例如：That you will win the medal seems unlikely.你能得奖看起来不大可能。
That light travels in straight lines is known to all.众所周知，光沿直线传播。
That you don’t like him is none of my business.你不喜欢他不管我的事。
(2)形式主语it替代主语从句位于句首，that引导真正的主语从句会放到句子的后面。
常用的句式主要有如下几种：1.It+系动词+形容词+that从句。
如：It is necessary that … 有必要 .....It is clear that … 很清楚.....It is likely that … 很可能.....It is important that … 重要的是.....类似的形容词还有：strange; natural; obvious; true; good; wonderful; possible; unlikely; quite; unusual; certain; evident; worth-while; surprising; interesting; astonishing, etc.例如：It was really astonishing that he refused to talk to you.It is essential that he should be here by the weekend.It seems obvious that we can not go on like this.It is necessary that you (should)master the computer.It is important that a student learn English well.It' s clear that they badly need help.It is likely that a hurricane will arrive soon.知识拓展：在“It is necessary / important/surprising/strange/unthinkable/unbelievable/incredible+that 从句”这类主语从句结构中，从句中谓语动词常用(should) +动词原形”，形式，即要用虚拟语气should 可省略。
高考英语主语从句定义：用作主语的从句叫主语从句，它是名词性从句之一。
主语从句的时态：不受主句的时态影响和限制。
引导主语从句的连接词有：从属连词: that, whether；连接代词: who (whoever), whom, whose, what (whatever)和which (whichever)；连接副词: when, where, how和why。
连接词：1. 从属连词：that，whether1）that引导主语从句只起引导作用，在主语从句中不充当任何成分，that本身无实际意义，但不能省略。
2）whether意为“是否”，放在句首句末皆可。
由whether引导的名词从句做主语，表语，介词宾语，同位语时！不可用if代替。
a.That price will go up is certain.b. Whether they would support us was a problem. 他们是否会支持我们还是一个问题。
2. 连接代词who ，what ，which, whatever, whichever, whoever (Who, whom, which, what可以和ever构成合成词，和what一样引导从句，ever起到强调作用。
此类主语从句不能用形式主语it引导，它们在句子中担任成分，不能省略，语序为陈述语序，既有疑问含义,又起连接作用,同时在从句中充当各种成分。
Which side will win is not clear. Whoever breaks the law will be punished.Whatever he did is right. Who killed the scientist remains a question.1）What和that引导的主语从句的区别：that 只起引导作用，不充当任何成分，没有意思。
What 不仅起引导作用，还要充当一定成分(主语、宾语或表语)，意思是：“什么”。
1〕从属连词：that，whether等.that 引导主语从句只起引导作用，本身无实际意义，在主语从句中不充当任何成分，但不能省略。
That he will win is certain.他肯定会赢。
Whether he’ll come here isn’t clear. 他是否会来这里还不清楚。
注意: 由that 引导的主语从句有时为了使句子结构平衡, 防止“头重脚轻”, 常用it 作形式主语, 而把从句放在后面。
例如:1. That he will refuse this piece of advice is impossible.2.That they should like each other is natural.这样就构成了下面一些常用句型:1) It is + n. +从句It is a pity/shame that... 遗憾的是……It is a surprise that…令人惊奇的是…It is a fact that… …是事实It is common knowledge that… …是常识______________(很遗憾)we lost the match._____________(这是事实)he cheated in the exam.2) It is + adj. +从句It’s certain that… 肯定…It is possible that... 很可能……It is unlikely that... 不可能……It is obvious that… 很明显…It is necessary \important \natural\... that…+(should) do________________(很可能)she will come back tomorrow.*_________________(很明显)this measure is effective.3) It +不及物动词+从句It happened that... 碰巧……It occurred to me that…我突然想起…_______________(刚好)I came into the office at that time.*____________________(我突然想起)I forget to sent the letter.4) It + be +过去分词+从句It is said that... 据说……It is known to all that... 众所周知……It is reported that... 据报道……It is believed that..人们相信/认为……It is suggested that + (should〕do... 建议……__________________(据报道)20 people were killed in the accident.*_______________(建议)we should eat more vegetable and do more exercise.2.连接代词who ，what ，which, whatever, whichever, whoever(Who, whom, which, what可以和ever构成合成词，和what一样引导从句，ever起到强调作用。
主语从句1．定义：用作主语的从句叫做主语从句。
2．引导主语从句的关联词有三类：（1）从属连词that、whether。
如：如:That they were in truth sisters was clear from the facial resemblance between them。
很明显，她们确是亲姐妹，她们的脸型很相似.Whether he’ll come here isn’t clear。
他是否会来这里还不清楚。
从属连词：that， whether等.that 引导主语从句只起引导作用,本身无实际意义，在主语从句中不充当任何成分，但不能省略.由whether及其他连词引导的主语从句放在句首，句后都可. If只能放在句中.造句:1。
、很明显他是个好人.2。
、他通过了考试让妈妈很高兴。
3、天气是否会转晴还不确定。
(3）（特殊疑问词）连接代词who, whom， whose， what, which, whoever， whatever, whichever 如：__________watch was lost is unknown.__________she did is not yet known. 她干了什么尚不清楚.__________side will win is not clear。
__________comes is welcome。
不论谁来都欢迎。
__________ was said has left us much to think。
这里说的话都应当保密.造句：1. 我们需要的是时间。
2。
谁将成为我们的班长还没有决定。
3。
哪本书更好还不知道。
(4) （特殊疑问词）连接副词 where, when, how， why，wherever，whenever，however。
___________ he did it remains a mystery.When they will start is not known yet.How this happened is not clear to anyone。
主语从句：即在复杂句中充当主语成分的句子例如"That he finished writing the composition in such a short time surprised us all"，他在很短的时间内写完作文让我们都很惊讶, 此复合句主要描述的是某事让我们惊讶，某事就是该复合句的主语，因此"That he finished writing the composition in such a short time" 便是该复合句的主语从句。
主语从句使用陈述语序，其通常结构为“引导词+ 主语+ 谓语+ 其他成分”；但当连接代词同时充当从句主语时，其结构为“连接代词+ 谓语+ 其他成分”。
时态：主语从句的时态不受主句时态的影响和限制引导主语从句的连词主要有:从属连词:that、whether （只起连接作用，不充当句子成分）连接代词:who、whoever、whom、whose、what 、whatever 、which 、whichever （既有连接作用，又做从句的主语、宾语、表语或定语）连接副词:when、where 、how 、why whenever、wherever（既有连接作用，又做从句的状语）例句：1. that引导例句：That you are coming to London is the best news I have heard this long time. 你将来伦敦是好久以来我听到的最好消息。
2. whether引导例句：Whether they would support us was a problem. 他们是否会支持我们还是一个问题。
3. 连接代词引导例句：Whoever is top from wins the game when two matched players meet. 两强相争勇者胜。
名词性从句之主语从句一、名词性从句概述：在句子中起名词作用的各种从句统称为名词性从句。
根据它们在句中的语法作用，这类从句又可分为主语从句、同位语从句、表语从句和宾语从句。
二、主语从句定义：在句中起主语作用的从句称为主语从句。
引导主语从句的连接词主要有：单纯连词（that, whether/ if）、连接代词(what, whatever, who, whoever, whom, whose, which, whichever等)和连接副词(when, where, why, how, whenever, wherever, however等)。
1)that引导的主语从句（1）由连词that引导的主语从句:引导词that无含义/在句中不做成分/不可以省。
例如：That you will win the medal seems unlikely.你能得奖看起来不大可能。
That light travels in straight lines is known to all. 众所周知，光沿直线传播。
That you don’t like him is none of my business.你不喜欢他不管我的事。
（2）形式主语it替代主语从句位于句首，that引导真正的主语从句会放到句子的后面。
常用的句式主要有如下几种：1.It+ 系动词+形容词+that从句。
如：It is necessary that …有必要……It is clear that …很清楚……It is likely that …很可能……It is important that …重要的是……类似的形容词还有：strange; natural; obvious; true; good; wonderful; possible; unlikely; quite; unusual; certain; evident; worth-while; surprising; interesting; astonishing, etc.例如： It was really astonishing that he refused to talk to you.It is essential that he should be here by the weekend.It seems obvious that we can not go on like this.It is necessary that you （should）master the computer.It is important that a student learn English well.It’s clear that they badly need help.It is likely that a hurricane will arrive soon.知识拓展：在“It is necessary / important/surprising/strange/unthinkable/unbelievable/incredible+that 从句”这类主语从句结构中，从句中谓语动词常用“（should）＋动词原形”，形式，即要用虚拟语气,should 可省略。
2023年高中英语语法精讲—主语从句详细讲解主语从句结构及用法在句子中担当主语的从句就叫做主语从句，通常放在主句谓语动词之前或由形式主语it代替，而本身放在句子末尾。
通常结构为“引导词 + 主语 + 谓语 + 其他成分"。
一. 概念：在句子中担当主语的从句就叫做主语从句，通常放在主句谓语动词之前或由形式主语it代替，而本身放在句子末尾。
主语从句使用陈述语序，其通常结构为“引导词 + 主语 + 谓语 + 其他成分", 但当连接代词同时充当从句主语时，其结构为“连接代词 + 谓语 + 其他成分”。
二. 引导词：1. that引导eg. That you are coming to London is the best news I have heard this long time.2. whether引导eg. Whether they would come to conference was a question.3. 连接代词引导: who,whom, whose, what, which, whoever, whomever, whichever, whatevereg. Whoever is top from wins the game when two matched players meet.4. 连接副词引导: therefore, besides, otherwise, however, moreover, still, thus, meanwhileeg. How this happended is not clear to anyone.5. 关系代词型what引导三. 形式主语it:1. 对关系代词型what引导的主语从句，可以使用形式主语。
eg. It is clear enough what he meant.2. 如果句子是疑问句，则必须用带形式主语it的结构.eg. Is it true that all of us need to to conference?如果一个句子在复合句中充当一个主语,那么这个句子就是主语从句。
主语从句讲解主语从句主语从句定义:在句子中担当主语的是一个从句,这个从句就叫做主语从句。
主语从句是在复合句中充任主语的从句，通常放在主句谓语动词之前或由形式主语it代替，而本身放在句子末尾。
1.引导主语从句的关联词有三类：(1)从属连词that，whetherThat they were true sisters was clear from the facial resemblance between them.Whether he’ll come here isn’t clear.(2)连接代词who, whom, whose, what, which, whoever, whatever, whichever，What she did is not yet known.How this happened is not clear to anyone.Whoever comes is welcome.(3)连接副词where，when, how, why2.主语从句是在复合句中充任主语的从句，其功同名词一样。
为了避免头重脚轻，常用it作形式主语,而把真正主语放在句子末尾。
How the book will sell depends on its author.That he is the best student in the class is obvious.= It is obvious that he is the best student in the class.注意：主语从句不可位于句首的五种情况(1) if引导的主语从句不可居于复合句句首。
(2) It is said , (reported) …结构中的主语从句不可提前。
例如：It is said that President Jingo will visit our school next week.(3) It happens…, It occurs…结构中的主语从句不可提前。
高中英语从句之主语从句讲解（特殊句式系列）（专门句式系列）一，that引导然而补充当成分的主语从句That the man can get it is known to all=It's known to all that the m an can get it那个男人能得到它是众所众知的。
1，It's important that you can learn English well你能学好英语是专门重要的2，It's known that you are so strong你专门强壮是众所周知的。
二，if 和whether 做的连接词的主语从句It is not sure whether he will come to your house or not 他是否来你家是不确定=Whether he will come to your house or not is not sureIt is not sure if he will come to your house三，疑问代词引导的主语从句What you can see is true 你所看到的差不多上确实Whom you are talking with is my friend 你正在谈天的那个人是我的朋友What I want are the bags on the desk 我所想要的是在桌子上的包。
What I want is a bag on the desk 我所有想要的是在桌子上的那个包。
It is true what you can see 你所看到的差不多上确实It is a bag on the desk what I want四，it 做形式主语的几种形式1，常用形容词：Certain 明确的，clear 清晰的，important重要的，natural自然的，nec essary必要的，obvious明显的，unbelievable 难以置信的，strange 惊奇的，unlikely不可能的，right 正确It is unlikely that you can lift the big stone 你能举起那个大石头是不可能的。
