高考必考语法精讲精练语法专题十：名词性从句名词性从句是比较重要的语法项目。
《2017年普通高等学校招生全国统一考试大纲》附录语法项目表中对名词性从句列了四项：主语从句、宾语从句、表语从句和同位语从句。
全国卷新课标Ⅰ对名词性从句的考查一般在语法填空和短文改错中，主要考查从句引导词的用法。
2015年高考全国卷Ⅰ没有考查名词性从句。
2016年高考全国卷Ⅰ第71题（短文改错）考查了宾语从句的引导词，My uncle is the owner of a restaurant close to that I live.本句中须将that改为where。
2017年高考全国卷Ⅰ没有考查了名词性从句。
在复合句中起名词作用的从句叫做名词性从句。
名词可以充当句子的主语、宾语、表语和同位语，因此，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。
①What was most important to her was her family.(主语从句)②I don’t know what you want to say.(宾语从句)③The good news is that we have won the game.(表语从句)④The news that we have won the game is true.(同位语从句)注意：连词that在引导名词性从句时无词义，不充当句子成分，只起连接作用，在主语从句、表语从句和同位语从句中不能省略，在引导宾语从句时，口语或非正式的文体中常被省去；疑问代词、疑问副词、缩合连接词以及关联短语在句中既保留自己的含义又起连接作用，在从句中充当成分。
名词性从句一般都用陈述句．．．的语序，即使从句表达的是疑问含义。
例如：①The problem is what he has done to the little boy.②We all don’t know when he will come.1. 主语从句在复合句中作主语的句子叫主语从句主语从句通常由从属连词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。
例如：①That he stole a bike was true.②What he wants to tell us is not clear.③Who will win the match is still unknown.④Where the English evening will be held has not yet been announced.⑤Whether he can pass the exam depends on whether he study hard or not.⑥Whatever you do is none of my business.⑦Whoever comes to our library will be welcome.单个的主语从句作主语时，谓语动词用单数形式。
如果是两个或两个以上的主语从句作主语，谓语动词则用复数形式。
例如：①Where and when he was born has not been found.②When the person was murdered and why he was murdered are still unknown.主语从句比较长的时候，为避免句子头重脚轻，常用it 代替主语从句作形式主语放于句首，而把主语从句置于句末。
主句的谓语动词一般用单数形式。
常用句型如下：（1）It + be + 名词+ 主语从句。
例如：①It is a fact that he has gone abroad.②It is a pity that you missed the sports meeting last week.（2）It + be + 形容词+ 主语从句。
例如：①It is obvious that he told a lie.②It is certain that he will win the game.（3）It + be + 过去分词+ 主语从句。
例如：①It is said that she will come to the party tomorrow.②It has not been announced when the plane are to take off.（4）It + 不及物动词+ 主语从句。
例如：①It happened that the meeting was canceled that day.②It occurred to me that I had forgotten to bring my wallet.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，常用的句型是：It is necessary/important/natural/strange/essential, etc.) that … 例如：①It’s necessary that you should study hard.②It is strange that he should say that.③It is essential that a college student should master at least a foreign language.2. 宾语从句在复合句中作宾语的从句叫宾语从句。
引导宾语从句的关联词与引导主语从句表语从句的关联词大致一样，在句中可以作谓语动词或介词及非谓语动词的宾语。
例如：①I want to know what he has told you.②She always thinks of how she can work well.③She will give whoever needs help a warm support.1).由连接词that引导的宾语从句由连接词that引导宾语从句时，that在句中不担任任何成分，在口语或非正式的文体中常被省去。
但如从句是并列句时,第二个分句前的that不可省。
例如：He has told me (that) he will leave Wuhan and that he will go to Shanghai tomorrow.注意:在insist,suggest, advise,decide, demand, desire,require, request,order, command等表示“坚持、建议、决定、要求、命令”（“坚决要命”）等意义的动词后，宾语从句中谓语部分常用虚拟语气，即should+ 动词原形。
例如：①I insist that she (should) do her work alone.②The commander ordered that troops (should) set off at once.但是, 如果suggest作“表明、暗示”讲, insist作“坚持说、坚持认为”讲，则其后的宾语从句中用陈述语气。
例如：①The smile on his face suggested that he had passed the examination.②The boy insisted that he had not stolen the money.2).用whether或if引导的宾语从句whether和if均可引导动词后的宾语从句，常可互换。
但从句中有or not时或介词后的宾语从句中只能用whether连接。
其它名词性从句，如主语从句、表语从句、同位语从句中表示“是否”只用whether. 介词后的宾语从句一般不用which和if引导，要用whether和what。
that 也很少引导介词宾语从句，只在except, but, besides等之后才用。
例如：①I don’t care about whether you have money or not.②Everything depends on whether we have enough money.③He seldom loses his temper except that you make a fool of him.3).宾语从句中的时态呼应宾语从句的谓语动词时态受主句谓语动词的影响，如果主句的谓语动词是一般现在时，从句中的谓语动词可以用各种时态。
例如：①I know that he studies English every day.②I know that he studied English last term.③I know (that) he will study English next year.④We all know that he has studied English since 1998.如果主句中的谓语动词用了一般过去时，则从句中的语动只能用过去时的某种形式，如一般过去时，过去进行时，过去将来时等。
例如：①We believed that he had earned enough money to build a house.②The teacher told us that Tom had left us for America．当从句表示的是客观真理，科学原理，自然现象，则从句仍用现在时态。
例如：The teacher told us that the sun rises in the east.4).当主句是I/ We think (suppose, expect, believe, guess, imagine) 时，其后的宾语从句如果是否定形式，常把否定词not从从句中转移到主句中成为否定的转移。
例如：①We don’t believe that he will win the game.②I don’t think he will do so.注意：doubt用于肯定结构时，后面用whether/ if 引导名词性从句；用于否定结构或疑问结构时，后面用that 引导名词性从句。
be sure 用于肯定句或疑问句时，后接that 引导的名词性从句；用于否定句时，后接whether/if 引导的名词性从句。
例如：①I doubt whether he will come tomorrow.②There is no doubt that he will come tomorrow.③I am sure that he will win the game.④I am not sure whether he will win the game.3. 表语从句在复合句中作表语的句子叫表语从句。