名词性从句
一， 名词性从句的概念：
1, 相当于名词，分为主语从句、表语从句、宾语从句和同位语从句
2，名词性从句的引导词：
that, whether, if (一般是宾语从句)，as if(表语从句)，who, whom, whose, what, which, when, where, why, how,以及由how组成的词组， 如：how many, how long, how far
两组需要注意的连接词
that/what
1）that和what都可以引导名词性从句，但that是连接词，本身无词义，仅起连接作用，不在从句中担任任何成份；what是连接代词，不仅引导名词性从句，而且在从句中充当一定的成份，如主语、宾语或表语。
e.g: That he stole a bike was true.
The important thing is what you do, but not what you say.
高考真题：
_______ we can't get seems better than _______ we have.
A. What; what B. What; that C. That; that D. That; what
2）whether和if均可引导动词后的宾语从句，常可互换。
a.在介词后面只能用whether，不能用if。
例如： ①This depends upon whether we are determined to do it.
b. 在动词不定式之前，只能用whether，不能用if。
例如： ①He doesn't know whether to stay or not.
c.引导主语从句，表语从句，同位语从句时只能用whether。
例如： ①It is unknown whether he will come. 他是否来还不知道。
②The question is whether they can take our advice.
3.The question whether he'll come is unknown.
3）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。
e.g：We doubt whether/ if he can win the game.
二， 各从句的使用及注意事项
（一） 主语从句：
1.充当主语的句子即主语从句。
（That he will come） is certain.
（Which team will win the match） is a matter of public concern.
2.名从的数：
1）用一个句子做主语时谓语动词用单数：
e.g: What you said ____ always right.
2) 主语连接的是两个或者两个以上的从句时，谓语动词用复数
e.g：What we will start and where we will go ___(have) not decided yet.
3）主语连接的是两个或两个以上的连接词时，谓语动词用单数。
e.g：When and where we will go ___ (have) not decided yet.
3.形式主语：
主语较长时，多在句子的后面，用it为形式主语。主要是：
It + be + adj + that
e.g：It is probable that he told her everything.
It + be + n + that
It is no surprise that our team should have won the game.
It + be + p.p + that
It is said that Jack drives badly.
It + seem/happen + that
It seems that Alice is not coming to the party.
☆：主语从句that不能省略。只可用whether不用if。
（二）表语从句
1,表语从句放在系动词之后
2,系动词：be动词，感动词，表动词
The truth is （that I have never been there.）
It looks （as if it were going to rain.）
3，as/as if/as though引导的表语从句常跟在特定动词后面，
如seem，appear，look，taste，sound，feel等。如：
①It sounds as if someone is knocking at the door．听上去好像有人在敲门。
②At that time，it seemed as though I couldn’t think of the right word．当时我似乎怎么也想不出一个恰当的字眼来。
（三）宾语从句
1,宾语从句放在动词介词之后：
Do you think （my clothes fit well?）(动宾)
Are you sorry for （what you’ve done?） (介宾)
2，时态一致原则
1） 如果主句谓语动词为现在时或将来时，从句中的谓语可以不受影响，根据具体的
情况来定。
e.g：Has he told you when he received the gift？
Will you tell me how you two are getting along？
2） 如果主语谓语动词为过去时，从句谓语一般要跟着改为相应的过去时。
e.g：I didn＇t know where they lived.He thought he was working for the people.asked him how long he had been waiting.
3）当宾语从句表示永恒真理时谓语可以不变
e.g：This proved that the earth is round.
3，另外有形式宾语it的形式。
We thought it strange that Mike did not come yesterday.
that引导的宾语从句做介词的宾语很少，只在except, but, besides之后，其他的介词要加that宾语从句，用it 做形式宾语。
The girl has not changed at all except that she is no longer so talkative.
You may depend on it that they will support you.
4， 否定前移和反义疑问句（宾语从句）
否定前移的条件：
1） 主句主语是第一人称
2） 常需要前移的词：think, believe, suppose, except, fancy, consider
不能使用否定前移的情况
1）think 等动词前有副词或者表示强调的do 时：
e.g: I really except he won’t fail the examition.
I do think that he is not fair.
2）think 等词和其他词构成并列的谓语时
e.g: I think and hope that he won’t cheat at cards.
3）think 作为插入语时
e.g: His decision is not wise, I think
5.考查名词性从句的虚拟语气问题
It is necessary that a college student ______ at least a foreign language.
A. masters B. should master C. mastered D. will master
分析:本题选B.句子的意思是:大学生至少应该掌握一门外语。It作形式主语,that引导的主语从句中谓语动词用虚拟语气。
(1) 在主语从句中用来表示惊奇、不相信、惋惜、理应如此等,谓语动词用虚拟语气(should) +do\常用的句型有:
I. It is necessary (important, natural, strange, etc.) that...
II. It is a pity(a shame, no wonder, etc.) that...
III. It is suggested (requested, proposed, desired, etc.) that...如: It is strange that she (should) think so.
(2) 表示建议、请求、命令、要求、坚持等及物动词后面的宾语从句中要用虚拟语气,常用的这类动词有suggest, propose, insist, desire, demand, request, order, command等。如:
I insist that she (should) do her work alone.
(3) 主语是suggestion, proposal, request, decision等表示\"建议、请求、要求、决定等\"意思的词时,表语从句中谓语动词要用虚拟语气\"(should) +do\"。如:
His suggestion is that we (should) hold another meeting to discuss the question.
(4) 表示\"建议、请求、命令、要求、决定等\"意思的名词后面的同位语从句中谓语动词要用虚拟语气\"(should)+do\"。如:
They received orders that the work(should)be done at once.
（5）两个特例：insist和suggest
insist ：
A）作“坚决认为”解释时，其后面的宾语从句用陈述语气。如：
I insisted to everyone that he was wrong．我对每个人坚持说他错了。
The Arab insisted that he had never seen the camel．
这阿拉伯人坚持说他从没看见过这头骆驼。
B）作“坚决主张、坚决要求”解释时，其后面的宾语从句要用虚拟语气，即宾语从句的谓语用（should）do sth． 如：
I insisted that he（should）go to see my father．我坚决要他去见我的父亲。
The Arab insisted that they（should）look for the camel．
这阿拉伯人坚持要他们去寻找这头骆驼。
C）同时，我们也可以用insist on sth．或insist on doing sth．来表达上述的两种意思。如：
I insisted on my correctness．（＝I insisted that I was correct．）我坚持认为自己是对的。
He insists on his innocence．（＝He insists that he is innocent．）他坚持认为自己无罪。
We all insist on not resting until we finish the work．（＝We all insist that we〈should〉not rest until we finish the work．）我们都坚决要求不完工就不休息。
He insists on my being present at the meeting．（＝He insists that I〈should〉be present at the meeting．）他一定要我出席这个会议。
suggest：
A）作“使想起、暗示、表明”解释时，其后面的宾语从句用陈述语气。如：
Her expression suggested that she was angry．她的表情显示出她生气了。
Are you suggesting that he is too old for the job？
你的意思是说他年纪太大了而不能干这工作？
B）作“建议”解释时，其后面的宾语从句用虚拟语气，也就是说宾语从句的谓语用（should）do sth． 如：
I suggested that she（should）leave early for the airport．
我建议她早点儿动身去机场。
He suggested that I（should）wear a jacket．他建议我穿一件夹克衫。
C）我们也可以用suggest（one ／one's） doing sth．来表达“建议”。如：
I suggested our class holding a meeting to discuss the problem．（＝I suggested that our class〈should〉hold a meeting to discuss the problem．）
我建议我们班开个班会讨论这个问题。
He suggested putting off the sports meet to the next week．（＝He suggested that the sports meet〈should〉be put off to the next week．） 他建议运动会推迟到下周。
（四）同位语从句
1，同位语从句在句中作某一名词的同位语，一般位于该名词（常见的fact, news, hope, truth, idea, suggestion, thought, question, order, problem, belief, doubt, fear…）, 常见的引导词that, whether等。
e.g：We all know the truth that the earth goes round the sun.
2.同位语从句的that不能省略。
3.同位语从句和定语从句的差别：
同位语从句：说明内容，that不是从句中的一个成分。
定语从句：说明性质和特征，that是从句中的一个成分。
e.g：He put forward the suggestion that the second question should be discussed first. (同位语从句)
The suggestion that he had put forward was turned down. （定语从句）
三、高考名词性从句规律性总结
规律一: that 引导陈述句作主语从句，that 只起连接作用，在从句中不充当成分, that 不能省（除宾语从句）.
规律二: that 在名词性从句中不作任何句子成分;
what 在引导名词性从句时，充当成分, 如:主语,宾语,表语
what = something that; all that /everything that; the + n. + that
规律三: 主语从句,宾语从句在适当的情况下可以借助“it”而后置。
规律四:名词从句中须使用陈述语序！
规律五:主句谓语动词是过去时态，从句也必须使用过去相应的时态。
规律六:下列情况下，用whether而不用 if ：
（1）主语从句或宾语从句置于句首时；
（2）前面有介词；
（3）引导表语从句、同位语从句时；
（4）与or not连用
（5）动词 discuss 后的宾语从句中
规律七: whoever = anyone who + 定语从句
whomever=anyone whom +定语从句
What/whatever , when / whenever , where / wherever 的含义基相同，只是后者比前者语气更重。在意义上也有细微差别： whatever 含义为 anything that；whenever 含义为 any time when ；wherever 含义为 any place where
规律八:that引导的同位语从句与定语从句的区别:
（1）that 引导定语从句时, 是关系代词,做主语或宾语
（2）that 引导同位从句时,是连词,不做成分,只起连接作用,that不能省. 如：idea, news, promise, fact、thought、reply、report、question、hope、word、suggestion、doubt 等用来表示它们的具体内容, 引导词有连词that, 副词how, when, where等。
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