高考英语名词性从句讲解
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
suggest的名词        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:
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
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。
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:. 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 is in the morning that the murder took place. 
. whoever, whatever, whichever等词可以引导主语从句,
但no matter who, no matter what 等不能.
Whoever breaks the school rules must be punished.
试比较:Whoever breaks the schools rules, he must be punished.
            =No matter who breaks the school rules, he must be punished.
1、It + be + 名词 + that从句
  It is a fact that---事实上…
  It is a pity that---可惜的是…
  It is a question that---…是个问题
  It is a honor that---…非常荣幸
  It is a shame that---…真是可耻
  It is common knowledge that---毫不奇怪的是…
2、It + be + adj. + that从句
  It is certain that---很肯定…
  It is natural that---很自然…
  It is obvious that---很显然…
  It is clear/evident that---很清楚…
  It is fortunate that---很幸运…
  It is better that---最好…
  It is likely/ probably/ possible that---很有可能…
3、It + be + 过去分词 + that 从句
  It is said that---据说…
  It is believed that---人们认为…
  It is reported that---据报道…
  It is not known that---….不为人知
  It is to be discussed that—…要讨论
  It has been proved that---…已证明
  It must be pointed out that---必须指出…
  It is estimated that---据估计…
4、It + 动词 + that从句
  It seems that---好像是…
  It happened that---碰巧…
  It turned out that---结果…
  It follows that---由此可见…
  It matters that---要紧的是…
  It occurred to me that---我想到…
  It struck me that---我想到…
5、 主语从句中的虚拟语气 
It is suggested, ordered, proposed, required, demanded, requested, insisted, desirable, advisable, imperative…….that-clause
It is important, necessary, natural, strange……that-clause
It is a pity, a shame, no wonder……that-clause 
Is it necessary that he (should) take the examination? 
It is strange that he (should) tell you this. A. would tell   
2. wh-引导的主语从句
句首
How the prisoner escaped is a mystery.
What he need is more experience.
用形式主语it来引导句子
It has not been decided yet whether she will go by bus or by train.
It is not very clear what they are talking about.
活学活用一
1. It has been proved _______ eating vegetables in childhood helps to protect you against serious illness in later life.
2.       you can’t make great progress in the language learning has something to do with your vocabulary.
3. It has come to be realized ______ particular matters in the air expose us to life’s real danger.
4. ______ I can’t understand is why the illegal cooking oil, mostly made from discarded (被弃的)kitchen waste, is difficult to detect and identify efficiently.
5. _________ countries having great difficulties in economy right now need most of all is financial aid rather than lecturing.
2)表语从句表语从句和主语指同一内容,它对主语进行解释说明,使主语的内容具体化。表语从句放在连系动词之后,充当复合句中的表语,一般结构是“主语十连系动词+表语从句”。
可以接表语从句的连系动词有 be, look, remain, seem 等。
1. The problem is that millions of people die of illnesses caused by smoking.
2. The question remains whether we can win the people. 
1. that 引导的表语从句
The fact is that he didn’t notice the car till too late.
One advantage of living in the country is that one can get close to nature.
2. wh- 疑问词引导的表语从句
The problem is how we can keep in touch with them.
This was why the complained about the assignments.
表语从句注意点
(1) 表语从句一律用陈述句的语序.
(2) 表语从句的引导词that无实际意义,但不能省略.
(3) 表语从句只能用whether,而不能用if 引导.
(4) 不要使用 The reason … is because that … 句型, 应使用 The reason… is that… 或 This / it /that/is because…等句型.
(5) 表语从句和同位语从句中的虚拟语气 
在 suggestion, proposal, idea, plan, order, advice 等名词后面的表语从句、同位语从句中要用虚拟语气,即(should)+动词原形。
My idea is that we (should) get more people to attend the conference.
I make a proposal that we (should) hold a meeting next week.