发布者：王桂芹 所属单位：鹿邑县第二高级中学 发布时间：2018-02-20 浏览数( -) 【举报】
名词性从句常考点
一、定义：在主从复合句中，具有名词或代词的功能并在句子中分别作主语、宾语、表语、同位语的从句叫作名词性从句。名词性从句包括主语从句、宾语从句、同位语从句和表语从句。
二、引导名词性从句的词叫连接词。
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(在句子中作主语、宾语、表语、补足语或定语)what，whatever，who，whoever，whom，whose，which ；连接副词（在句子中作状语 ）when，where，how，why。
主语从句
一、定义：在复合句中用作主语的从句叫主语从句。
二、连接词：that，whether，what，whatever，who，whoever，whom，whose，which，when，where，how，why。
三、【句式研读】：
观察下列句子，注意主语从句的用法。
1. What surprised me most was that the little girl could play the violin so well.
2. Who will go to the concert is not known.
3. That she was chosen made us very happy.
4. Whether she will come or not is still a question.
5. Which book they will choose is still unknown.
6. When we shall hold our sports meet is not decided.
7. It’s strange that he knows nothing about it.
8. It is a pity that she has made such a mistake.
9. It is said that President Xi Jinping will visit our school next week.
四、【归纳总结】：
(一).语序
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”，如句1、2。
(二).引导词
1）. that引导主语从句时无词义，也不充当任何成分，但通常不可以省略，如句3；
2）. whether引导从句时意为“是否”，通常不能用if来代替,通常whether，if后接从句为肯定句。
如句4；（注意：whether，if常跟跟定的主语从句）
3）.可以引导从句的连接代词主要有：who, whom, whose, what, which, whatever, whoever等，如句5；
4）. 可以引导从句的连接副词主要有：where, when, how, why等，如句6。
(三).常见句型
有时为保持句子平衡，常用it作形式主语，代替从句放在句首，而把主语从句置于句末。常用句型如下：
1）. It + be + 形容词 + that 从句， 如句7;
2）. It + be + 名词 + that 从句， 如句8;
3）.It + be + 动词的过去分词 + that 从句，如句9；
此种句式可转化成从句主语+be+ 动词的过去分词+动词不定式结构，（如句9转化成President XiJinping
is said to visit our school next week.）。
(四).此种句子的主要特征是，都在主从复合句中充当主语，并通常放在主句谓语动词之前或由形式主语it代替，而从句本身放在句子末尾。
五、 主语从句主要类别：
（一）、由连词that或whether 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。
（1）That you will win the medal seems unlikely.你想获得奖牌看起来是不可能的。
（2）That you are so indifferent bothers me.你如此冷淡使我很烦恼。
（3）That she survived the accident is a miracle.她在事故中幸免于难简直是奇迹。
2） 用连词 whether 引导的主语从句:whether有含义(是否),在句中不做成分,也不可以省。
Whether she is coming or not doesn’t matter too much.她来不来都无关紧要。
（二） 用连接代词引导的主语从句(在由连接代词who, whose, whom, which, what, whoever, whomever, whichever, whatever引导的名词性从句中，其连接代词在句中起名词或形容词性作用，在主语从句中担当一定成分。注：连接代词连接的主语从句在整个句子中所做的成份与连接代词本身在主语从句中所做的成分在多数情况下不尽相同。).
（1）What you need is more practice.你所需要的是更多的训练。（注：what在主语从句中做need的宾语）
（2）hat I want to know is this. 我想知道的就是这事。（注：what在主语从句中做know的宾语）
（3）Whatever we do is to serve the people.我们无论做什么都是为人民服务。
（三）用连接副词when, where, why, how引导的名词性从句(其连接副词有含义,在句中作状语。)
（1）Where we should leave it is a problem.
（2）When they will come hasn’t been made pubic.什么时候来还不知道。
六、【特别提醒】:
1）.为了保持句子平衡，常用it 做形式主语置于句首,而将主语从句放在句末（尤其是当谓语部分较短时）。
（1）That light travels in straight lines is known to all.光沿直线传播，这是众所周知的事。
=It is known to all that light travels in straight lines.众所周知光沿直线传播。
（2）When the plane is to take off has not been announced .飞机何时起飞还没有宣布。
= It has not been announced when the plane is to take off.还没有宣布飞机何时起飞。
(当what引导的主语从句表示“…的东西”时，一般不用it作形式主语。)
错:It is a book what he wants.
对:What he wants is a book. 他想要的是本书。
2）.主语句变成疑问句，从句语序保持陈述语序
Has it been settled who will be sent to carry out the task ?谁将被派去执行这项任务决定了吗 ？
3）.固定句型用法：
（1） It is +名词+从句
It is a fact that… 事实是……
It is good news that … ……是好消息
It is a question that … ……是个问题
It is common knowledge that … ……是常识
类似的名词还有：a pity；a wonder；a good thing； no wonder； surprise等。
eg：It is a mystery to me how it all happened.这一切是怎么发生的是个谜。
It is common knowledge that the whale is not a fish.鲸鱼不是鱼，这是常识。
It is no surprise that Bob should have won the game.鲍勃会赢得这场比赛，这不足为奇。
（2） It is +形容词+从句
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.
eg：It is obvious that conductors and insulators are both important in industry.
很明显导体和绝缘体在工业中都很重要。
It is doubtful whether she will be able to come.她是否能来令人怀疑。
It was really astonishing that he refused to talk to you .他拒绝和你说话真是令人惊讶。
It is essential that he should be here by the weekend .周末之前，他应该到这里是必要的。
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 is +过去分词+从句
It is said that … 据说……
It is reported that … 据报道……
It is suggested that …有人建议……
It has been proved that … 已证明……
It must be proved that… 必须指出……
类似的过去分词还有：known; estimated; expected; believed; thought; hoped; noted; discussed; required; decided; suggested; demanded; made clear; found out,etc.
eg：It is thought that he is the best player.大家都认为他是最好的选手。
It is estimated that the vase is 2000 years old.据估计这个花瓶有2000年的历史。
It is used to be thought that a new star must be due to a collision between two stars.
过去一直认为新星是由于两颗星星之间碰撞产生的。
It has not been made clear when the new road is to be opened to traffic.
还没弄清楚这条路将在什么时候开始通车。
It does not matter if I missed my train, because there is another later.
没有赶上这趟火车没有关系，稍晚还有一趟。
It happened that I saw him yesterday.碰巧我昨天看见他了。
【注】当“及物动词 + 宾语”较短时，也可用这种结构。
eg：It shocked me that Peter did not tell anybody where he was.
让我吃惊的是彼得没有告诉任何人他在哪里。
It does not interest me whether you go or not.我对你去不去不感兴趣。
（4）.主语从句只用whether引导，而不用if引导。