高中三年级的日子是苦的，有刚入高中三年级时的迷茫和压抑，有成绩失意时的沉默不语，有晚上奋战到一两点的精神肉体双重重压，也有在清晨凛冽的寒风中上学的艰苦经历。在奋笔疾书中得到常识的快乐，也是一种在巨大重压下看上去茫然无助的痛苦。智学网高中三年级频道为你整理《高中三年级英语必修四要点总结：名词性从句的分辨办法》期望对你有帮！
主语从句
主语从句是在复合句中充当主语的从句，一般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，主如果为了平衡句子结构，主语从句的连接词没变化。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。
比如：
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。
It is +名词+从句
It is a fact that … 事实是…
It is an honor that …很荣幸
It is common knowledge that …是知识
it is +形容词+从句
It is natural that… 非常自然…
It is strange that… 奇怪的是…
it is +不及物动词+从句
It seems that… 好像…
It happened that… 碰巧…
it +过去分词+从句
It is reported that… 据报道…
It has been proved that… 已证实…
3. 主语从句不可坐落于句首的五种状况。
if 引导的主语从句不可居于复合句句首。
It is said ， …结构中的主语从句不可提前。
比如：
It is said that President Jingo will visit our school next week.
That President Jiang will visit our school next week is said.
It happens…， It occurs… 结构中的主语从句不可提前。
比如：
It occurred to him that he failed in the examination.
That he failed in the examination occurred to him.
It doesn’t matter how/whether …结构中的主语从句不可提前。
比如：
It doesn’t matter whether he is wrong or not.
Whether he is wrong or not doesn’t matter.
含主语从句的复合句是疑问句时，主语从句不可提前。
比如：
Is it likely that it will rain in the evening?
Is that will rain in the evening likely?
4. What 与that 在引导主语从句时有什么区别。
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。
比如：
1) What you said yesterday is right.
2) That she is still alive is a consolation.
宾语从句
宾语从句就是在复合句中作宾语的名词性从句，一般放在主句谓语动词或介词之后。
1. 作动词的宾语。
由that引导的宾语从句
比如：
I heard that be joined the army.
由what， whether 引导的宾语从句
比如：
1) She did not know what had happened.
2) I wonder whether you can change this note for me.
动词+间接宾语+宾语从句
比如：
She told me that she would accept my invitation.
2. 作介词的宾语。
比如：
Our success depends upon how well we can cooperate with one another.
3. 作形容词的宾语。
比如：
I am afraid 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 从句的看作缘由状语从句。
4. It 可以作为形式宾语。
It 不仅能够作为形式主语，还可以作为形式宾语而真的的宾语that 从句则放在句尾，尤其是在带复合宾语的句子中。
比如：
We heard it that she would get married next month..
5. 后边不可以直接跟that 从句的动词。
这种动词有Allow， refuse， let， like， cause， force， admire， condemn， celebrate， dislike， love， help， take， forgive等。这种词后可以用不定式或动名词作宾语，但不能用that引导的宾语从句。
比如：
I admire their winning the match.
I admire that they won the match.
6. 不可用that从句作直接宾语的动词。
有的动词不可用于“动词+间接宾语+that从句“结构中，容易见到的有Envy， order， accuse， refuse， impress， forgive， blame， denounce， advise， congratulate等。
比如：
He impressed the manager as an honest man.
He impressed the manager that he was an honest man.
7. 否定的转移
若主句谓语动词为Think， consider， wuppose， 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，从句谓语用一定式。
比如：
I don’t think this dress fits you well.
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，常见的还有the reason is that… 和It is because 等结构。
比如：
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.
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讲解，说明名词的具体内容，一般由that引导。
比如：
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. 同位语在句子中的地方。
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。
比如：
He got the news from Mary that the sports meeting was put off.
3. 同位语从句与定语从句有什么区别。
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，而同位语从句中的that是连词，只起连接主句与从句有哪些用途，不充当句中任何成分。
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，描述定的性质或特点;同位语从句是名词性的，其功能是对名词进行补充说明。比如：
1) The news that he told me is that Tom would go abroad next year.
2)The news that Tom would go abroad is told by him. 。
