高中英语语法讲解：名词性从句
一、概念
名词性从句在句子中起名词作用，它在整个句子中能担任主语、宾语、表语或同位语。根据它在句中充当的不同成分，名词性从句可分别称为主语从句、宾语从句、表语从句或同位语从句。
没有主语从句、宾语从句/表语从句，整个句子就缺少了主语/宾语/表语，句子结构不完整；没有同位语从句，句子结构完整，但句意不完整。
注：区别于定语从句（形容词性从句）：限制性定语从句相当于一个形容词，修饰主句中的某个名词，做它的定语；非限制性定语从句，几乎完全独立于主句，没有定从，虽然句意不一定完整，但句子结构仍然完整。
I know the girl who is reading over there.
He came home safe and sound, which was a great relief to his family.
二、4类连接词&注意点
1． that （1）连接主句与从句（2）无意义（3）不做从句中的成分（4）能否省略
2． if/whether （1）连接（2）表“是否”（3）不做成分（4）whether与if区别
3．疑问代词 what, who, whom, which &whatever, whoever, whomever, whichever（1）连接（2）表不同含义（3）做从句中的重要成分
4．疑问副词when, where, why, how（1）连接（2）表不同含义（3）做从句中的状语
三、四种名词性从句
1．主语从句
（1）普通主语从句
That he is still alive is sheer luck.注：that位于句首引导主从，一定不省。
Whether the plan is practicable remains to be seen.
What we need are many instructive books.
method形容词What we need is more time and money. 注：主从做主语，主句谓语动词一般用单数，但what引导的主从，根据后面表语的意义一致原则。
When and where the meeting will be held is not clear.
When Tom will come and what Lucy will say are not clear.注：一套主谓结构谓语动词用单数，两套则用复数。
Which team will win is hard to predict.
How he made such a large fortune is still a mystery.
（2）用it做形式主语为（避免头重脚轻）的主语从句，常见句型有：
It is a pity/a shame/no wonder/a pleasure/an honor/a fact/common sense/n that…
It is high/about time that…
It is the first/second/...time that…
It is obvious/strange/necessary/vital/essential/natural/not uncommon/ likely/
It is said/reported/announced /believed/estimated expected/recommended/pp that…
It happens that…；It turned out that…
It occur to/dawn on/hit/strike sb that…
It doesn’t matter that/whether/how…
注：连接代词一般不用it做形式主语，e.g. What he said interested me greatly.
2．宾语从句：
（1）做及物动词的宾语I don’t know what his name is.
（2）做介词的宾语
My teacher was satisfied with what I did.
The film reminded me of how my grandma brought me up.
At what I think is the appropriate time, I will tell you all the truth.
注：介词后面的宾从一般不用that引导，但in that 和 except that是例外
He differed from his classmates in that he devoted all his spare time to reading.
I know next to nothing about Tom except that he comes from the US.
（3）放表语形容词后的宾语从句
I am glad that you make it to my party.    She is not sure what will happen next.
（4）it做形式宾语
You may depend on it that I will always come to your aid.（介词后宾从）
I will see to it that everything goes smoothly.
I once took it for granted that my parents put my needs first.（动词+宾语+宾补结构）
I want to make it clear that I will never accept your money.
They think/consider it impossible that house prices will ever drop.
I like/hate it when …；I would appreciate it if…（句型）
注1：一个动词或介词后接一个以上宾从时，第一个宾从的that可省，第二个开始的that不可省
I forgot (that) my research paper was due on Tuesday and that I had left it unfinished since last Friday.
注2：宾从时态一般与主句时态呼应，客观真理自然现象除外。
In the middle age, people didn’t believe that the earth moves around the sun.
注3：否定前移I don’t think he is fit for the job, is he?
3．表语从句：
（1）be+表从
The problem is that he has never been to another country alone. 表从中that一般不省。
My question was why she turned my invitation down.
（2）句型：looks/seems/appears +as if/though…, “看起来似乎好像”
He looks as if he knew everything. (与事实相反，虚拟)
It seems as if our team is going to win.(与事实相符，真实)
（3）句型：that/this is why/because…, “这是因为/…的原因”
He was late for school yesterday. That was because he was ill.
He was ill. That was why he was late for school.
4．同位语从句
解释说明“某些抽象名词”的具体内容：news, word (单数:消息), belief, idea (主意), thought (想法), fact, truth, plan, notice (通知), promise等
比较特殊的有：doubt（有/无关于…的疑问）, possibility/chance（有/无…的可能性）, evidence（证据表明）。
I agree with your plan that we set out tomorrow morning.
Word came that he survived the war. 
There is no evidence that lives exist on Mars.
注：“无疑问/很确定”连接词用that；“有疑问/不确定”用whether
I have no doubt that…同位从；There is some doubt whether…同位从
= It is certain that…主从；It is uncertain whether…主从
四、细节考点
1. 从句语序：
（1）陈述句语序，I don’t know what your plan is. 特例：He refuses to tell me what is the matter.
（2）主句是疑问句用疑问语序，从句仍用陈述句语序
What do you think he is doing? What you think he is doing? (X)  What do you think is he doing? (X)
（3）名从中套强调句的情况下的疑问词放在最前面
I don’t know what it was that made him angry. I don’t know it was what that made him angry. (X)
2. 连接词that 的省略总结：

版权声明：本站内容均来自互联网，仅供演示用，请勿用于商业和其他非法用途。如果侵犯了您的权益请与我们联系QQ:729038198，我们将在24小时内删除。