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
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：
1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
①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。
②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：i. 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.
ii. 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
①句首
How the prisoner escaped is a mystery.
What he need is more experience.
②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.
