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名词性从句讲解在复合句中起名词作用的从句叫做名词性从句。
它包括主语从句、宾语从句、表语从句和同位语从句。
名词性从句是中学阶段的一个重要语法项目，在历年的高考中几乎都涉及到，并且每年的命题各有变化。
分析历届高考试题名词性从句考查的焦点主要有以下六个方面1. 考查名词性从句的语序问题2. 考查引导词that与what的区别3. 考查it在名词性从句中作形式主语或形式宾语的用法4. 考查whether与if的区别5. 考查名词性从句中的疑问词+ever引导的名词性从句与no matter+疑问词引导的状语从句的区别6. 考查名词性从句的虚拟语气问题语法要点剖析一、名词性从句主语从句、表语从句、宾语从句、同位语从句，在整个句子中所起的作用，相当于一个名词。
因此，这四种从句通称为名词性从句。
引导名词性从句的连接词可分为三类：连接词：that, whether, if （不充当从句的任何成分）连接代词：what, whatever, who, whoever, whom, whose, which.连接副词：when, where, how, why1. 主语从句作句子主语的从句叫主语从句。
主语从句通常由从属连词that，whether，if和连接代词what，who，which，whatever，whoever以及连接副词how，when，where，why等词引导。
that在句中无词义，只起连接作用；连接代词和连接副词在句中既保留自己的疑问含义、又起连接作用，在从句中充当从句的成分。
例如：What he wants to tell us is not clear. 他要跟我们说什么，还不清楚。
It is known to us how he became a writer. 我们都知道他是如何成为一名作家的。
Where the English evening will be held has not yet been announced.英语晚会将在哪里举行，还没有宣布。
高中英语名词性从句知识讲解以及练习题附答案一、名词性从句概述名词性从句是一种充当名词作用的从句，通常在主句中作主语、宾语、表语或同位语。
它通常由引导词（如that, whether, if, who, whom, whose, which, what等）引导，并且从句中含有一个主语和谓语。
名词性从句的种类有很多，包括主语从句、宾语从句、表语从句和同位语从句等。
下面我们将逐一介绍这些从句。
二、主语从句主语从句作为一个名词，通常位于句首，是一个句子，主要作用是作为主句的主语。
引导主语从句的词：What (什么)；Whether (是否)；If (是否)；That (那个)。
例句：What he said is true. (他说的是真的。
)Whether it will rain tomorrow is uncertain. (明天是否会下雨还不确定。
)If you go, I will go too. (如果你走，我也跟着走。
)That he is coming is good news. (他来的消息是好消息。
)注意：主语从句的谓语动词通常要用单数形式。
What引导的主语从句通常用来表示“事物”的概念。
三、宾语从句宾语从句是一个名词，通常位于主句的动词后面，作为主句的宾语。
它可以由常见的宾语从句引导词引导，例如whether, if, that, who, whom, whose, what, when, where, how等。
引导宾语从句的词：Whether (是否)；If (是否)；That (那个)；Who (谁)；Whom (谁)；Whose (谁的)；What (什么)；When (何时)；Where (何处)；How (如何)。
例句：I know that he is coming. (我知道他要来。
)I wonder if he is telling the truth. (我想知道他是否说了真话。
名词性从句讲解在复合句中起名词作用的从句叫做名词性从句。
它包括主语从句、宾语从句、表语从句和同位语从句。
一、名词性从句主语从句、表语从句、宾语从句、同位语从句，在整个句子中所起的作用，相当于一个名词。
因此，这四种从句通称为名词性从句。
引导名词性从句的连接词可分为三类：连接词：that, whether, if （不充当从句的任何成分）连接代词：what, whatever, who, whoever, whom, whose, which.连接副词：when, where, how, why1. 主语从句（两种结构，三类连接词）两种结构1.主语从句位于句首：What he wants is a book.Who kept the door open all night was unknown.2.主语从句位于句尾，it 作形式主语。
（1）It + be + 名词+ that从句It’s a pity that we can’t go. 很遗憾我们不能去。
It’s no surprise that our team should have wo n the game. 我们没赢这场比赛真意外。
（2）It + be + 形容词+ that从句.It seems obvious that we can not go on like this. 很明显我们不能这样下去了（3）It + be + 动词的过去分词+ that从句It is known to all that light travels in straight lines.众所周知光沿直线传播。
It is reported that China has sent another man-made earth satellite into orbit.（4）It + 不及物动词+ that 从句注意在主语从句中用来表示惊奇、不相信、惋惜、理应如此等语气时，谓语动词要用虚拟语气“(should) +do”，常用的句型有：It is necessary (important, natural, strange, etc.) that …It is a pity (a shame, no wonder, etc.) that…It is suggested (requested, proposed, desired, etc.) that…三类连接词:1.连词that whetherthat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。
名词性从句练习题及答案1. 主语从句：It is important that you finish your homework on time.- 答案：It is important that you finish your homework on time. (这是正确的句子结构，主语从句是 "that you finish your homework on time".)2. 宾语从句：I believe that he will succeed.- 答案：I believe that he will succeed. (宾语从句是 "that he will succeed".)3. 表语从句：The fact is that we have run out of time.- 答案：The fact is that we have run out of time. (表语从句是 "that we have run out of time".)4. 同位语从句：The news that he won the prize is exciting.- 答案：The news that he won the prize is exciting. (同位语从句是 "that he won the prize".)5. 宾语从句的疑问形式：What did he say he would do?- 答案：What did he say he would do? (宾语从句的疑问形式是"what he said he would do".)6. 宾语从句的否定形式：I don't think that he is honest.- 答案：I don't think that he is honest. (宾语从句的否定形式是 "that he is honest".)7. 宾语从句的省略：He promised to help us.- 答案：He promised to help us. (宾语从句的省略形式是"promised to help us".)8. 宾语从句的连接词：Whoever breaks the law will be punished. - 答案：Whoever breaks the law will be punished. (连接词是"whoever".)9. 宾语从句的时态：I heard that she had left the city.- 答案：I heard that she had left the city. (宾语从句使用了过去完成时 "had left".)10. 宾语从句的虚拟语气：I suggest that he study harder.- 答案：I suggest that he study harder. (宾语从句使用了虚拟语气 "study".)结束语通过这些练习题，学生可以加深对名词性从句的理解，提高在实际语境中运用这些从句的能力。
名词性从句同学们，在第3、4、5单元我们分别学习了宾语从句、表语从句、主语从句和同位语从句。
它们都属于名词性从句。
现在，我们将从下面几点谈谈名词性从句：一、相关概念；二、种类；三、常见引导词；四、七大常考考点：l.that \ what \ which; 2.it形式主语、宾语的用法；3.语序问题；4.同位语从句和定从的区别；5.what \ whatever… 6.if\whether;7.虚拟语气问题；五、相关习题集中练习一.相关概念1. 名词：表示人或事物的名称的词2. 名词的句法作用：名词在句中主要作主语，宾语，表语和同位语。
另外还可以作定语，状语3. 名词性从句：在英语的句子结构中，本来该由名词充当的主语、宾语、表语和同位语，由一个句子来充当，这个句子就叫：名词性从句。
二、名词性从句的种类1. When we will start is not clear.主语从句2. Mrs. Black won ' t belieV hat her son has become a thief.宾语从句3. My idea is that we should do it right now.表语从句4. I had no idea that you were her friend. 同位语从句三、常见引导词:1）从属连词that只引导，本身无意义，仅起引导作用。
（引导宾语从句时可省，但是如果是并列的多个宾语从句，只能省第一个）2）连接代词who, whom, what, which, whoever, whatever, whiche等e，有意义，作成分3）连接副词where, when, how, why等，有意义，在句中作状语4）从属连词if, whether （是否）（if只能引导动词、形容词之后的宾语从句）1. What he said has nothing to do with you.2. When we'start tomorrow will be told soon.3. That he did such a thin gsatisfied me.4. How we can protect cultural relics needs to be discussed.四、名词性从句七大常考考点考点1:A.连接词：that与what的区别What we can ' t get seems better tha h n at we have.That a new teacher will come to our school is true.that只起连接作用，无意义，在从句中不充当任何成分;what既有连接作用，又要在从句中作成分（主语，宾语，表语）（…的东西;物;话;时间;地点;人物擞目等不同概念）1. After five hours drive, they rea Wtedt was called the hometow n of the goddess.2. The other day, my brother drove his car down the street at what was a dangerous speed.3. The village was quite differe nt from what it used to be.4. That the earth is round is known to us all.5. Father made a promis&hat if I passed the exam in ati on he would buy me a computer.B. what （什么）/ which （表选择，哪一个）1. ---Do you know what Mr. Black ' s addres? is---He may live at No. 18 or No. 19 of Bridge Street. I whi o h not sure of2. I read about it in some books or other, does it mattewhich it was?咼考题选萃1) ____ y ou don ' t like him is none of my bus in ess.A. WhatB. WhoC. ThatD. Whether2) ___ h e said at the meeti ng ast oni shed everybody prese nt.A. WhatB. ThatC. The factD. The matter3) There ' s a feeling in me ___ we kn'w weve ra UFO is.A. thatB. whichC. of whichD. what考点2 : it作形式主语，形式宾语的用法A. it作形式主语1. 他犯了那样一个错误真是遗憾。
各类从句详解英语从句可以分为名词性从句、定语从句和状语从句三大类：下面我们逐一进行说明：一、名词性从句（主语从句、表语从句、宾语从句、同位语从句）主语从句、表语从句、宾语从句和同位语从句在复合句中的充当的成分和其名称相同，分别作主句的主语、表语、宾语和同位语。
上述这四种从句均被称为名词性从句。
所有的名词性从句均不能用逗号分开，并且它们都用相同的关联词，关联词如下：①主从连词：that (无意义), whether (是否), if (是否)（在句子中不充当任何成分）②连接代词：who (谁), whom (谁), whose (谁的), what (什么), which (哪一个)③连接副词：when (什么时候), where (什么地方), how (怎样), why (为什么)主从连词只起连接作用，连接代词和连接副词除了起连接作用外，还充当从句某一个成分。
另外，可以用whatever, whichever, whoever, who(m)ever等连接代词引导名词性从句，来加强语气。
下面分别对各种名词性从句进行介绍（一）主语从句（subject clause）在主句中用作主语的主谓结构称之为主语从句。
例如：That he will come to the discussion is certain.他来参加讨论是确定的。
That the moon moves round the earth is well known to all of us.月球绕地球转动，这是我们大家都熟知的。
When the meeting is to be held has not yet been decide.会议什么时候召开还没有决定。
主语从句放在句首，句子常常显得比较笨重，因此通常可以把it放在句首，作形式主语，而将主语从句放在后面。
例如上面的句子可以分别改写为：It is certain that he will come to the discussion.It is well known to all of us that the moon moves round the earth.It has not yet been decide when the meeting is to be held.下面再举一些例句：What they are after is profit.他们追求的是利润。
名词性从句用法讲解与专项练习题及答案名词性从句包括主语从句、宾语从句、表语从句和同位语从句。
高考常从连接词的选择、语序、语气、时态等方面来考查。
名词性从句中的连接词有连词that / whether / as if，连接代词what / who/ which /whose / whatever / whoever / whomever / whichever，连接副词where /when /why / how / wherever / whenever。
第1讲引导名词性从句的连接词\考点1. 引导名词性从句的连接词有哪些有学生认为，引导同位语从句只能用that, 这句话对吗先看下面几个句子。
①I have no question that he will come.②I have a question whether he will come③I have a question when he will come.我们可以看出：上面三个句子中question后面都是同位语从句，都是说明question的内容的。
~在句①中，同位语从句的原句是陈述句，由that引导；在句②中，原句是一般疑问句，由whether引导；在句③中，同位语从句的原句是特殊疑问句，特殊疑问词也起着连接作用。
其实，所有名词性从句的连接词都有上面的三种情况。
宾语从句：I don’t know that he will come.I don’t know whether/if he will come.I don’t know when he will come.【表语从句：What I don’t know is that he will come.What I don’t know is whether he will come.What I don’t know is when he will come.主语从句That he will come is obvious.Whether he will come isn’t known yet.When he will come isn’t known yet.^1. 【2010浙江】It is uncertain ______ side effect the medicine will bring about, although about two thousand patients have taken it.A. thatB. whatC. howD. whether2. 【2012全国新课标】It is by no means clear ______ the president can do to end the strike.A. howB. whichC. thatD. what3. 【2012山东】It doesn’t matter ______ you pay by cash or credit card in this store.A. howB. whetherC. whatD. why4. 【2013陕西】It remains to be seen ______ the newly formed committee’s policy can be put into practice.]A. thatB. whichC. whatD. whether5. 【2009天津】It is obvious to the students ______ they should get well prepared for their future.A. asB. whichC. whetherD. that6. 【2012江西】It suddenly occurred to him ______ he had left his keys in the office.A. whetherB. whereC. whichD. that考点2. 引导词that的省略问题主语从句、表语从句、同位语从句中连词that不能省略。
高中英语名词性从句详细讲解与练习在句子中起名词作用的从句叫名词性从句。
名词性从句的功能相当于名词词组，它在复合句中能担任主语、宾语、表语、同位语，因此根据它在句中不同的语法功能，名词性从句又可分为主语从句、宾语从句、表语从句、同位语从句。
引导名词性从句的词叫做连接词，包括：1.连词（在名词性从句中只起连接作用，不作成分）2.连接代词（在名词性从句中作主语、宾语或表语）3.连接副词（在名词性从句中作状语）所有的名词性从句的语序都是陈述语序。
I主语从句：是在主句中作主语的从句。
它由连接词引导，通常位于谓语动词之前。
连接词：1.连词：在从句中不充当任何成分，常见的引导主语从句的连词有that, whether oThat he got the first prize excited him much.他获得一等奖一事使他非常兴奋。
It is doubtful whether we can get there on time.我们能否按时到达那儿还不确定。
D that引导的主语从句:在从句中不作任何成分，也没有实际意义。
一般情况下that不可省略。
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.你不喜欢他不关我的事。
2）whether引导的土语从句:常置于句首，表示“是否”之意；if一般不引导主语从句。
Whether he can finish his task on time is of greatimportance.他是否能按时完成任务非常重要。
Whether you can succeed or not depends on howhard you work at it.你能否成功取决于你努力的程度。
2.连接代词：在从句中起名词或代词的作用，常作从句的主语、宾语、表语或定语,有具体意义且不能省略。
从句讲解：从句及其特点（学案）从句是指在一个句子中充当一个成分的句子，充当什么成分就叫什么从句，如：充当宾语就叫宾语从句，充当定语成分就叫定语从句。
从以上定义中我们可以得出关于从句的一个最大特点：从句是句子。
从句的共同特点：1.从句都有自己的连接词 2.从句都是陈述语序(陈述语序就是主语在前，谓语在后)1.名词性从句在句子中起名词作用的句子叫名词从句。
名词从句的功能相当于名词词组, 它在复合句中能担任主语、宾语、表语、同位语、介词宾语等，因此根据它在句中不同的语法功能，名词从句又可分别称为主语从句、宾语从句、表语从句和同位语从句。
引导名词性从句的连接词可分为三类：连接词：that, whether ,if (不充当从句的任何成分)连接代词：what, whatever, who, whoever, whom, whose, which连接副词：when, where, how, why如：That she was chosen made us very happy.宾语从句宾语从句是指在一个句子中充当宾语的句子，如：He said that he wanted to be a teacher when he grew up.宾语从句的特点：①宾语从句有自己的连接词②宾语从句用陈述语序③宾语从句的时态①宾语从句的连接词：宾语从句的连接词包括that、if/whether(是否)、特殊疑问词。
②宾语从句的语序;A.宾语从句的连接词后加陈述语序(主语在前，谓语在后),如：I want to know if he can come tomorrowB.当连接词本身又是宾语从句的主语时，后面直接加谓语动词，如：She asked me who had helped him.③宾语从句的时态，只要记住以下口诀“主现则从任，主过则从过，客观真理一般现”A.主现则从任：主句如果是一般现在时，则从句根据时间状语需要从八种时态中任选一种，如：1.He tells me he likes English very much(一般现在时)B.主过则从过：主句如果是一般过去时，则从句根据时间状语需要从四种带“过”字的时态中任选一种，带“过”字的时态分别是如：一般过去时，过去进行时，过去将来时，过去完成时。
名词性从句包括主语从句、宾语从句、表语从句和同位语从句。
名词性从句是一种具有名词功能的非独立分句。
具体用法见下表：主语从句大多数主语从句都可以用it作形式主语而把主语从句置于句尾。
(what引导的主语从句表示“……的东西”时，一般不用it作形式主语；whatever, whoever, whichever一般也不用it作形式主语。
)►It makes no difference where we shall have the meeting.我们在哪开会无所谓。
【注意】(1)常见的it替代that引导的主语从句的句式主要有以下几种：①It＋系动词＋形容词(necessary/right/likely/important/certain...)＋that从句②It＋be＋名词(短语)(a pity/a shame/good news/a fact/an honour...)＋that从句③It＋be＋过去分词(said/told/heard/reported/decided/suggested...)＋that从句④It＋特殊动词(seem/appear/happen/matter)＋that从句(2)在“It is necessary/important/natural...＋that从句”的结构中，从句谓语常用“(should ＋)动词原形”。
宾语从句1．动词find, feel, think, consider, make, believe等后有that引导的宾语从句作宾语补足语时，则常用it作形式宾语而将that宾语从句后置。
►I think it necessary that we take plenty of boiled water every day.我认为每天摄入足量的白开水很有必要。
2．有些动词(短语)不能直接跟宾语从句，需要借助形式宾语it。
常见的有hate, enjoy, like, dislike, love, appreciate, see to等。
高考英语名词性从句讲解及练习一、概念：名词性从句相当于名词词组，在复合句中起名词性作用。
分类：主语从句、表语从句、宾语从句和同位语从句。
引导名词性从句的1）连接词：that, whether, if;2）关系代词：who, whom, whose, what, which, whatever, whichever;3) 关系副词：when, where, how, why.二、要点：人物主语：who, whoever what, whatever宾语：whom, whomever what, whatever名词性从句表语：whom what定语：which what whose状语when where why how whenever however wherever不做成份：that if/whether as if /as though三、基础知识学习：1主语从句: 主语从句是在复合句中代替作主语的名词, 充当主语的从句，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.that 引导的主语从句①句首That a round-trip to Mars would take more than a year and a half is estimated.That he misunderstood me is obvious.That引导主语从句，放句首，不做任何成分，不可省略。
②用形式主语it来引导句子A. that引导主语从句放句首时，有时会为了避免头重脚轻，保持句子平衡，常用it做形式主语，把真正的that引导的主语从句放句后。
It is strange that he made no answer.It is known to all that the earth is round.B. 用it做形式主语的主语从句结构注意：i. It作形式主语和it引导强调句的比较It作形式主语代替主语从句，主要是为了平衡句子结构，主语从句的连接词没有变化。
专题三名词性从句名词性从句指在复合句中起名词作用的从句，它在句子中可作主语、宾语、表语或同位语。
名词性从句既是中学英语教课的要点，也是高考考察的热门。
一、名词性从句的分类名词性从句包含主语从句、宾语从句、表语从句和同位语从句。
其连结词有 that, if, whether；连结代词 who, what, which；连结副词 when, where, how, why 等。
考察热门一：对主语从句的考察主语从句在复合句中充任主语，它能够放在主句谓语动词以前。
但为了保持句子均衡，多半状况下可用it 作形式主语，而把主语从句置于句尾。
考察热门二：对宾语从句的考察宾语从句在句子中作及物动词或介词的宾语。
假如主句的谓语动词是及物动 make, find, see, think 等，则把宾语从句置于宾语补足语以后，用it 作形式宾语。
此外，某些作表语的形容词，如 sure, happy, glad, certain 等以后也能够带宾语从句。
考察热门三：对表语从句的考察表语从句在句子中作表语，位于主句中的系动词以后。
考察热门四：对同位语从句的考察同位语从句一般跟在某些抽象名词以后，进一步说明该名词所表示的详细内容。
可跟同位语从句的名词主要有：fact, idea, news, promise, belief, condition, doubt, fear, hope, problem, proof, question, reply, report, suggestion, thought, truth等。
二、对名词性从句的考察应注意以下几点：考察热门五：考察名词性从句的语序和主从句时态名词性从句均应用陈说句语序，其时态要保持主从句时态一致性。
考察热门六：从语境和句子构造需要出发，选择适合的连词（I）连词that 和what：that 无实质意义，在从句中不充任任何成分，只起连结主从句的作用；如 that 指引宾语从句，常可省略；如指引主语从句、表语从句或同位语从句， that 不可以省略。
名词性从句名词性从句（主语从句，表语从句，宾语从句，同位语从句）1.that 引导的名词性从句，that 在从句中不充当任何句子成分，没有词义。
that引导宾语从句时常可省略，但如果引导两个以上宾语从句时，that不省。
引导主语从句时常可用it 作形式主语That light travels in straight lines is known to all.众所周知光是以直线运行的。
（主语从句）=It is known to all that light travels in straight linesThe reason for his absent was that he was ill.他缺席的原因是他病了。
（表语从句）I think( that) you are right.我认为你是对的。
（宾语从句）The news that our football team has won is true.我们足球队赢了的消息是真的。
（同位语从句）注意区别：The news( that/which) he told me is true.他告诉我的消息是真的。
（定语从句）2.what 引导的名词性从句，what 在从句中必须要作主语，宾语，表语,常译作“所---的”或“什么”,what 一般不引导同位语从句What we need is water.我们所需要的是水。
（主语从句）What we need are useful books.我们所需要的是有用的书。
（主语从句）This is what I want to say.这就是我想说的。
（表语从句）Please tell me what she is saying.请告诉我她在说什么。
（宾语从句）3.how,where,when,why,等引导的名词性从句，保留疑问词的原意，或译为-“--的地方”“---的时候”Do you know how he came here?By bus.你知道他是怎么来的吗？乘公共汽车。
名词性从句在句子中起名词作用的句子叫名词性从句(Noun Clauses）。
名词性从句的功能相当于名词词组, 它在复合句中能担任主语、宾语、表语、同位语、介词宾语等，因此根据它在句中不同的语法功能，名词从句又可分别称为主语从句、宾语从句、表语从句和同位语从句。
一．主语从句主语从句是在主句中作主语的句子，它由连接词引导，通常位于谓语动词之前。
1. 连词：在从句中不充当任何成分，常用见的引导主语从句的连词有三个，即that, whether和if.That he got the first prize excited him much. 他获得一等奖一事使他非常兴奋。
Whether you can succeed or not depends on how hard you work at it. 你能否功取决于你努力的程度。
注意：whether引导的主语从句常用置于句首，表示“是否”之意；if引导主语从句时不置于句首。
2. 连接代词：在从句中起名词或代词的作用，常作从句的主语、宾语、表语或定语，有具体意义且不能省略。
常见的连接代词有who, whom, whose, what, which, whoever, whomever, whatever, whichever.What we should do with the problem is undecided. 我们如何处理这上问题还未作出决定。
3. 连接副词：在从句中起副的作用，常作从句的状语，表示时间、地点、原因、方式等。
常见的连接副词有when, where, how, why, whenever, wherever, however等。
How they will solve the serious problem has not been decided. 他们将如何解决这个严重的问题还没有决定。
Why he did that wasn’t quite clear. 他为什么做那件事还不十分清楚。
名词性从句名词性从句相当于名词，可分别作主句的主语、表语、宾语和同位语。
因此，名词性从句分为主语从句、表语从句、宾语从句和同位从句。
（一）引导名词性从句的连接词类别词义在从句中的作用that 无任何词义仅起连接作用，在从句中不充当任何句子成分；一般可以省略，但是在句首不可省略。
if和whether 意为“是否”，表明从句意义的不确定性起连接作用，在从句中不充当任何句子成分关系代词：who,what,which,whom, whose,whatever,whoever, whomever, whichever 有各自自身的意义起连接作用，并在从句中充当主、表、宾、定语等关系副词：when,where,why,how,however,wh enever, wherever 有各自自身的意义起连接作用，并在从句中充当状语（二）主语从句1.主语从句在复合句作主语。
e.g. Who will go is not important.2.that引导主语从句时，不能省略。
e.g. That he suddenly fell ill last week made us surprised.3.用it作形式主语，主语从句放在句末。
It+系动词+形容词+that从句. necessary,right,likely,wrong,important,certain,clear...It+系动词+名词+that从句. a pity, a shame, a fact,no wonder...It+be +动词ed+that从句. said,told,reported,suggested,considered....It+特殊动词+that从句. seem,turn out,appear,matter...e.g. It doesn’t matter so much whether you will come or not.4.whether引导的主语从句可放句首，而if引导的主语从句不能放句首，只能放句末。
名词性从句用法详解一、概说名词性从句，即指性质相当于名词的从句，它包括主语从句、宾语从句、表语从句和同位语从句。
从高考的考查的实际情况来看，名词性从句考得最多的是宾语从句，其次是主语从句，再次是表语从句，而同位语从句则很少考查。
引导名词性从句的连接词可分为三类：连接词：that, whether, if （不充当从句的任何成分）连接代词：what, whatever, who, whoever, whom, whose, which.连接副词：when, where, how, why二、名词性从句的一般引导词1. 连接词that 只起连接作用，没有任何意思，也不充当句子成分，在宾语从句中可省略，但引导其他名词性从句时通常不省略。
I hope (that) you enjoy your holiday. 希望你假期过得好。
（宾语从句）That he likes you is very obvious. 很显然他喜欢你。
（主语从句）2. 连接词whether 也不充当句子成分，但有自己的意思，表示“是否”；引导宾语从句时，可换成if，但引导其他名词性从句时不能换成if。
如：He asked whether [if] I would show him the way. 他问我是否可以给他带路。
Whether it will do us harm remains to be seen. 是否对我们有害还要看一看。
(引导主语从句，不能用if 代替whether)3. 连接代词who(m), whose, which, what 等，均有各自的意义，在从句中作主语、宾语、定语等。
如：That’s what she wanted to do. （表语从句）Who will help us is not known. （主语从句）Tell me which one you like best. （宾语从句）4. 连接副词when, where, why, how 等，也各自有自己的意义，在从句中作状语。
高中英语讲义---- 名词性从句（主从、表从、宾从，同从）1，陈述句做名从用连词that + SV, that 表主句肯定从句完整，不做成分。
主从可用it 做形式主语，宾从第一个that 可省略。
You study hard.主从：That you study hard is known to us.= It is known to us that you study hard.表从：My opinion is that you study hard .宾从：I think (that) you study hard. …and that (不能省略)….同从：My opinion that you study hard is known to us. *比较同从和主从！●一般抽象名词后对其进行解释和说明的完整句子就是其同位语从句，不完整就是定语从句。
I appreciate your idea that we have an exam every week. （that后完整—同从）I appreciate your idea that you came up with last time.（that后不完整---定从）2，一般问句做名从用连词whether(是否) + SV，whether表主句不肯定从句完整，宾从中可用if（介词后或宾从后有or not时只用whether）。
Does your friend like English ?主从：Whether your friend likes English isn’t clear .=It isn’t clear whether your friend likes English.表从：My question is whether your friend likes English.宾从：I don’t know whether/ if your friend likes English.同从：My question whether your friend likes English isn’t clear.3, 特殊问句做名从用疑问词（连词）+ SV, 疑问词做主语时直接+谓语。
名词性从句名词性从句是在句子中起名词作用的句子。
名词性从句的功能相当于名词词组，它在复合句中能担任主语、宾语、表语、同位语、介词宾语等，因此根据它在句中不同的语法功能，名词性从句又可分别称为主语从句、宾语从句、表语从句和同位语从句。
连接词引导名词性从句的连接词可分为三类：1.连词：that （本身无意义。
引导单一的宾语从句时that常可省略，但引导主语从句、表语从句、同位语从句时that通常不被省略）whether,if （均表示“是否”）as if ,as though （均表示“好像”，“似乎”）◆以上在从句中均不充当任何成分2.连接代词：what/ whatever, who/ whoever, whom/ whomever, whose/whosever, which/whichever.有词意，在从句中充当主语，宾语，表语，定语等。
3.连接副词：when/ whenever, where/ wherever, how/ however, why.有词意，在从句中充当状语。
主语从句作句子主语的从句叫主语从句。
主语从句通常由连词that，whether，和连接代词what，who，which，whatever，whoever以及连接副词how，when，where，why等词引导。
that 在句中无词义，只起连接作用；连接代词和连接副词在句中既保留自己的疑问含义、又起连接作用，在从句中充当一定的成分。
主语从句后的谓语动词一般用单数形式。
例如：What he wants to tell us is not clear. 他要跟我们说什么，还不清楚。
Who will win the match is still unknown. 谁能赢得这场比赛还不得而知。
It is known to us how he became a writer. 我们都知道他是如何成为一名作家的。
Where the English evening will be held has not yet been announced. 英语晚会将在哪里举行，还没有宣布。
名词性从句名词性从句（主语、表语、宾语、同位语从句）（一）主语从句1．定义：用作主语的从句叫做主语从句。
2．2．构成：关联词+简单句3．3．引导主语从句的关联词有三类：4．(1) 从属连词that。
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。
(2) 从属连词whether。
如：Whether he’ll come here isn’t clear. 他是否会来这里还不清楚。
(3) 连接代词who, whom, whose, what, which, whoever, whatever, whichever连接副词 where, when, how, why。
如：What she did is not yet known. 她干了什么尚不清楚。
解释：1．主语从句能用it作形式上的主语。
常以it作形式主语的句型有：A. It+be+形容词(obvious, true, natural, surprising, good, wonderful, funny, possible, likely, certain, probable, etc.)+that从句。
如：It is certain that she will do well in her exam. 毫无疑问她考试成绩会很好。
B. It+be+名词词组(no wonder, an honour, a good thing, a pity, no surprise, etc.)+that 从句。
如：It’s a pity that we can’t go. 很遗憾我们不能去。
C.It+seem, happen等不及物动词及短语+that从句。
如：It seems that Alice is not coming to the party at all. Alice似乎不来参加晚会。
D.It+doesn’t matter (makes no difference, etc.)+连接代词或连接副词引起的主语从句。
如：It doesn’t matter whether she will come or not. 她是否来这无关紧要。
F. 当that引导的主语从句出现在疑问句中时，要以it作形式主语，而把主语从句后置。
如：Does it matter much that they will not come tomorrow? 他们明天不来很要紧吗？G. 当主语从句出现在感叹句中时，要以it作形式主语，而把主语从句后置。
如：How strange it is that the children are so quiet! 孩子们这么安静真奇怪！2．注意连接代词whoever, whatever, whichever等引导主语从句的含义Whoever comes will be welcome. (whoever=the person who) 来的人将受到欢迎。
（二）表语从句1．定义：用作表语的从句叫做表语从句。
2．构成：关联词+简单句3．引导表语从句的关联词的种类：(1) 从属连词that。
如：The trouble is that I have lost his address. 麻烦是我把他的地址丢了。
(2) 从属连词whether, as, as if。
如：He looked just as he had looked ten years before. 他看起来还与十年前一样。
注：从属连词if一般不用来引导表语从句，但as if却可引导表语从句能跟表语从句的谓语动词一般为系动词be, seem, look等。
如：It looked as if it was going to rain. 看起来天要下雨了。
(3)连接代词who, whom, whose, what, which, whoever, whatever, whichever连接副词 where, when, how, why。
如： The question is how he did it. 问题是他是如何做此事的。
解释：1．连词because可引导表语从句。
如：I think it is because you are doing too much. 我想这是因为你做得太多。
2．在一些表示“建议、劝说、命令”的名词后面的表语从句中，谓语动词用虚拟语气。
should+动词原形表示，should可省略。
如：My suggestion is that we (should) start early tomorrow. 我的建议是我们明天一早就出发。
注意：1．what引导●“…….+ is = “…….+ is .….是表语从句”例：Raw material is what we are badly in need of.= Raw material is the thing that we are badly in need of.2．when、where、why、whether、how引导●“…….+ is +when、where、why、whether、how表语从句”，表示“.….是表语从句”例：That’s where we differ.●表语从句中只能用whether表示是否例：The question is whether we can finish our work by tomorrow morning. 3．that引导●“…….+ is /remain/look/seem/appear + that表语从句”，表示“.….是表语从句”例：What’s troubling me is that I don’t have much experience in this field.●主语是reason时，表语从句必须由that引出例：The reason I don’t go there was that I got a new job.4．as if/as through引导●“……look/seem/appear/remain（系动词）+ as if/as through 表语从句”，表示“.….好像表语从句”例：It looks as if it is going to rain.（三）宾语从句1．定义：用作宾语的从句叫宾语从句。
2．构成：关联词+简单句3．引导宾语从句的关联词有三类：(1) 从属连词that。
如：He told us that he felt ill. 他对我们说他感到不舒服。
注： that在引导宾语从句时也并不是任何情况下都可以省略。
在以下情况下，that不能省略。
1． Everybody could see what happened and that Tom was frightened.(and连接两个宾语从句，that宾语从句放在and的后面时，that不能省略。
)大家都会看出发生的事情并知道Tom非常害怕。
2．I know nothing about him except that he is from the south.(that引导的宾语从句作介词宾语时，that不能省略。
)对他我一无所知，只知道他是南方人。
3．That he ever said such a thing I simply don’t believe. (that从句位于句首时，that不可省略。
)我简直不相信他曾说过这样的话。
4． We decided, in view of his special circumstances, that we would admit him for a probationary period. (主句谓语动词与that从句之间有插入语，that不可省略。
)鉴于他的特殊情况，我们决定应允他一段试用期。
(2)从属连词if/whether。
如：I doubt whether he will succeed. 我怀疑他是否会成功。
(3)连接代词who, whom, whose, what, which, whoever, whatever, whichever连接副词 where, when, how, why。
如：Who or what he was, Martin never learned.(1) 介词宾语从句宾语从句也可用作介词的宾语。
如：He was deeply displeased by what had occurred that day.他对那天发生的事感到很不快。
I walked over to where she sat. 我走向她坐的地方。
有时介词可以省略。
如：I don’t care (for) who marries him. 我不管谁跟他结婚。
解释：1．如果宾语从句后还有宾语补足语，则用it作形式宾语，而将宾语从句后置。
如：We thought it strange that Xiao Wang did not come yesterday.我们认为小王昨天没来是奇怪的。
He has made it clear that he will not give in.他已表明他不会屈服。
2．作介词的宾语：连词that引导的名词性从句很少作介词的宾语，只用在except, but, in后。
其他一些介词的宾语从句如果由连词that引导，则需用it先行一步，作形式宾语。
如：He is a good student except that he is careless.他是一个好学生，只是有点粗心。
You may rely on it that I shall help you. 你可以指望我会帮助你的。
介词宾语不可以用which来引导，而要用what来引导。
如：Are you sorry for what you've done?你为你所做的一切感到内疚吗？3．某些形容词或过去分词后常接宾语从句，这类形容词或过去分词有sure, glad, certain, pleased, happy, afraid, surprised, satisfied等，连词that可省略。
如：I am not sure what I ought to do.我不能确定我该做什么。
4．连词whether (…or not)或if引导的宾语从句if和whether引导的宾语从句可以互换使用，但whether常和or not连用，if一般不与or not连用。
