備戰2020屆高考英語（通用版）一輪復習專題04 名詞性從句
一、主語從句
主語從句是在復合句中充當主語的從句，通常放在主句謂語動詞之前或由形式主語it代替，而本身放在句子末尾。
1.it 作形式主語和it引導強調句的比較
it 作形式主語代替主語從句，主要是為了平衡句子結構，主語從句的連接詞沒有變化。而it引導的強調句則是對句子某一部分進行強調，無論強調的是什么成分，都可用連詞that。被強調部分指人時也可用who/whom。如：
it is a pity that you didn’t go to see the film.你沒去看那場電影真是遺憾。
it doesn’t interest me whether you succeed or not.你成功與否對我沒有什么吸引力。
2.用it 作形式主語的結構
1)it is ＋名詞＋從句
it is a fact that ...事實是……
it is an honor that...非常榮幸
it is common knowledge that...……是常識
2)it is ＋形容詞＋從句
it is natural that...很自然……
it is strange that...奇怪的是……
3)it is ＋不及物動詞＋從句
it seems that...似乎……
it happened that...碰巧……
4)it ＋過去分詞＋從句
it is reported that...據報道……
it has been proved that...已證實……
3.主語從句不可位于句首的五種情況
1)if 引導的主語從句不可居于復合句句首。
2)it is said ，(reported)...結構中的主語從句不可提前。如：
據說江主席下周要來我校視察。
it is said that president jiang will visit our school next week.(right)
that president jiang will visit our school next week is said.(wrong)
3)it happens...，it occurs... 結構中的主語從句不可提前。如：
他考試沒及格。
it occurred to him that he failed in the examination.(right)
that he failed in the examination occurred to him.(wrong)
4)it doesn’t matter how/whether ...結構中的主語從句不可提前。如：
他是不是錯了，這一點不重要。
it doesn’t matter whether he is wrong or not.(right)
whether he is wrong or not doesn’t matter.(wrong)
5)含主語從句的復合句是疑問句時，主語從句不可提前。如：
傍晚有可能下雨嗎？
is it likely that it will rain in the evening? (right)
is that will rain in the evening likely? (wrong)
4.what 與that 在引導主語從句時的區別
what 引導主語從句時在從句中充當句子成分，如主語、賓語、表語，而that 則不然。如：what you said yesterday is right. 你昨天說的是對的。
二、賓語從句
賓語從句就是在復合句中作賓語的名詞性從句，通常放在主句謂語動詞（及物動詞）或介詞之后。
1.作動詞的賓語
1)由that引導的賓語從句（that 通常可以省略）,如：
i heard that he joined the army. 我聽說他參軍了。
2)由what，whether (if)引導的賓語從句，如：
she did not know what had happened. 她不知道發生了什么事。
3)動詞＋間接賓語＋賓語從句。如：
she told me that she would accept my invitation. 她跟我說她愿意接受我的邀請。
2.作介詞的賓語，如：
our success depends upon how well we can cooperate with one another.