Question

什么叫名词性从句？

重点区讲一下同位语从句，宾语从句和主语从句。谢谢~

Answer 1

名词性从句是由if, whether, that 和各种疑问词充当连接词所引导的从句，其功能同名词一样。
一．主语从句
主语从句是在复合句中充当主语的从句，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. 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。而it引导的强调句则是对句子某一部分进行强调，无论强调的是什么成分，都可用连词that。被强调部分指人是也可用who/whom。例如：
It is a pity that you didn’t go to see the film.
It doesn’t interest me whether you succeed or not.
It is in the morning that the murder took place.
It is John that broke the window.
2. 用it 作形式主语的结构
(1) It is ＋名词＋从句
It is a fact that … 事实是…
It is an honor that …非常荣幸
It is common knowledge that …是常识
(2) it is ＋形容词＋从句
It is natural that… 很自然…
It is strange that… 奇怪的是…
(3) it is ＋不及物动词＋从句
It seems that… 似乎…
It happened that… 碰巧…
(4) it ＋过去分词＋从句
It is reported that… 据报道…
It has been proved that… 已证实…
3. 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. (right)
That President Jiang will visit our school next week is said. (wrong)
(3) It happens…, It occurs… 结构中的主语从句不可提前。例如：
It occurred to him that he failed in the examination. (right)
That he failed in the examination occurred to him. (wrong)
(4) It doesn’t matter how/whether …结构中的主语从句不可提前。例如：
It doesn’t matter whether he is wrong or not. (right)
Whether he is wrong or not doesn’t matter. (wrong)
(5) 含主语从句的复合句是疑问句时，主语从句不可提前。例如：
Is it likely that it will rain in the evening? (right)
Is that will rain in the evening likely? (wrong)
4. What 与that 在引导主语从句时的区别
What 引导主语从句时在句时在从句中充当句子成分，如主语．宾语．表语，而that 则不然。例如：
1) What you said yesterday is right.
2) That she is still alive is a consolation.
二．宾语从句
宾语从句就是在复合句中作宾语的名词性从句，通常放在主句谓语动词（及物动词）或介词之后
1. 作动词的宾语
(1) 由that引导的宾语从句（that 通常可以省略）,例如：
I heard that be joined the army.
(2) 由what, whether (if) 引导的宾语从句，例如：
1) She did not know what had happened.
2) I wonder whether you can change this note for me.
(3) 动词＋间接宾语＋宾语从句。例如：
She told me that she would accept my invitation.
2. 作介词的宾语
例如：Our success depends upon how well we can cooperate with one another.
3. 作形容词的宾语
例如：I am afraid (that) I’ve made a mistake.
That 引导的从句常跟在下列形容词后作宾语：
Anxious, aware, certain, confident, convinced, determined, glad, proud, surprised, worried, sorry, thankful, ashamed, disappointed, annoyed, pleased, hurt, satisfied, content 等。也可以将此类词后的that 从句的看作原因状语从句。
4. It 可以作为形式宾语
It 不仅可以作为形式主语，还可以作为形式宾语而真正的宾语that 从句则放在句尾，特别是在带复合宾语的句子中。 例如：
We heard it that she would get married next month..
5. 后边不能直接跟that 从句的动词
这类动词有Allow, refuse, let, like, cause, force, admire, condemn, celebrate, dislike, love, help, take, forgive等。这类词后可以用不定式或动名词作宾语，但不可以用that引导的宾语从句。例如：
I admire their winning the match. (right)
I admire that they won the match. (wrong)
6. 不可用that从句作直接宾语的动词
有些动词不可用于“动词＋间接宾语＋that从句“结构中，常见的有Envy, order, accuse, refuse, impress, forgive, blame, denounce, advise, congratulate等。例如：
He impressed the manager as an honest man. (right)
He impressed the manager that he was an honest man. (wrong)
7. 否定的转移
若主句谓语动词为Think, consider, believe, expect, fancy, guess, imagine等，其后的宾语从句若含有否定意义，一般要把否定词转移到主句谓语上，从句谓语用肯定式。例如：
I don’t think this dress fits you well.（我认为这件衣服不适合你穿。）
三．表语从句
表语从句在复合句中作表语的名词性从句，放在系动词之后，一般结构是“主语＋连系动词＋表语从句”。可以接表语从句的连系动词有be, look, remain, seem等。引导表语从句的that常可省略。另外，常用的还有the reason is that… 和It is because 等结构。例如：
1) The question is whether we can make good preparation in such a short time.
2) This is why we can’t get the support of the people
3) But the fact remains that we are behind the other classes.
4) The reason he is late for school is that he missed the early bus.
四．同位语从句
同位语从句就是在复合句中作名词的同位语的名词性从句。
1. 同位语从句的功能
同位语从句对于名词进一步解释，说明名词的具体内容，一般由that引导，例如：
1) The king’s decision that the prisoner would be set free surprised all the people.
2) The order that all the soldiers should stay still is given by the general.
2. 同位语在句子中的位置
同位语从句有时可以不紧跟在它所说明的名词后面，而是被别的词隔开。例如：
He got the news from Mary that the sports meeting was put off.
3. 同位语从句与定语从句的区别
(1) 定语从句中的that既代替先行词，同时以在从句中作某个成分（主语或宾语），而同位语从句中的that是连词，只起连接主句与从句的作用，不充当句中任何成分。
(2) 定语从句是形容词性的，其功能是修饰先行词，对先行词加以限定，描述定的性质或特征；同位语从句是名词性的，其功能是对名词进行补充说明。例如：
1) The news that he told me is that Tom would go abroad next year.（他告诉我的消息是汤姆明年将出国。）（第一个that引导的从句是定语从句，that在从句中作宾语）
2)The news that Tom would go abroad is told by him.（汤姆将出国的消息是他讲的。）（同位语从句，that在句中不作任何成分）

Answer 2

在句子中起名词作用的句子叫名词从句 (Noun Clauses）。 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。 宾语从句是名词性从句的一种,名词性从句包括主语从句,表语从句,同位语从句,宾语从句。
1. 主语从句：主语从句在句中做主语。它可以放在主句谓语动词之前，但多数情况由 it 作形式主语，而把主语从句放在主句之后。
①What we will do next is unknown to all. 接下来做什么大家都不知道。
②It is a pity that you should miss the bus. 真遗憾，你错过了那班公共汽车
2. 表语从句：表语从句在句中作表语，位于主句中的系动词之后，如： The question is who can complete the difficult task . 问题是谁能完成这项艰巨的任务。
表语从句还可用 as if引导。
He looked as if he was going to impress everything in the room into his mind. 他看上去是要把屋里的一切都印入脑海
4. 宾语从句
(1)宾语从句在句中作及物动词或介词的宾语。
①We can learn what we did not know. 我们可以学习我们所未知的。
②He was very pleased with what you had said at the meeting. 他对你会上所言十分满意。
如果主句的谓语动词是及物动词make, find, see, hear等，则把宾语从句置于宾语补足语之后，用it 作为形式宾语。
We find it necessary that we practise spoken-English every day.
我们发现每天练习英语口语是很必要的。
另外，某些带宾语的形容词，如 sure, happy, glad, certain等之后也可带宾语从句。(注：有的语法学家认为是省略了形容词后的介词) 。
I am sure that he will succeed. 我相信他会成功的。
注意(1)关联词只能用 whether 不能用 if 表示“是否”的情况如下：
A. 在表语从句和同位从句中。
①The question is whether the film is worth seeing. 问题是这部电影是否值得一看。②The news whether our team has won the match is unknown. 我们队是否赢得比赛的消息还是未知的。
B. 在主语从句中，只有用it 作形式主语时，whether 和if都能引导主语从句，否则，也只能用 whether。
①Whether we shall attend the meeting hasn’t been decided yet.
②It hasn’t been decided whether (if) we shall attend the meeting.
我是否出席会议还没有决定。
C. 在介词之后。(介词往往可以省略)。
It all depends (on) whether they will support us. 这完全在于他们是否支持我们。
(2)关联词if, whether均可使用的情况如下：
A. 引导宾语从句。
I wonder if (whether) the news is true or not. 我琢磨这个消息是否属实。
B. 在“be＋形容词”之后。
He was not sure whether (if)it is right or wrong. 他不能确定那是对还是错。
(3)关联词只能用whether或if, 不能用that 的情况如下：
若doubt一词作“怀疑”解接宾语从句时，主语为肯定句用whether或if, 主句为否定句或疑问句用that。
①I doubt whether he will come soon. 我怀疑他是否会很快来。
②I do not doubt that he will come soon. 我不怀疑他会很快来。
③Do you doubt that he will come soon? 你怀疑他是否会很快来。
注意：下面这个例句中doubt的含义为“认为……未必可能”。
I doubt that he will come. 我怀疑他未必会来
　

Answer 3

在句子中起名词作用的句子叫名词从句,可分别称为主语从句、宾语从句、表语从句和同位语从句。