人教考点 20 主语从句&表语从句&同位语从句（重难考点精讲练）(解析版)-备战2023年高考英语.docx

考点 20 主语从句&表语从句&同位语从句（重难考点精讲练）
考向二 主语从句
1.主语从句在复合句中充当主语，大多数主语从句都可以用it作形式主语而把主语从句置于句尾。
2.that引导主语从句时可用it作形式主语，that不可省；what引导的主语从句表示＂……的东西＂时，一般不用it作形式主语；whatever，whoever，whichever一般也不用it作形式主语。
☞That she will succeed is certain.
常见的it替代that引导的主语从句的句式主要有以下几种：
(1)It＋系动词＋形容词(necessary，right，likely，unlikely，wrong，important，certain，clear，obvious，strange，normal等)＋that从句
☞It is certain that most of the farmers have brought in more money by all means.
(2)It＋be＋名词(短语)(a pity，a shame，good news，a fact，an honour，a wonder，no wonder等)＋that从句
It’s no wonder that you’ve achieved so much success.
(3)It＋be＋过去分词(said，told，heard，reported，decided，suggested，advised，ordered，remembered，thought，considered，well­known，announced等)＋that从句
☞It is said that the professor has already succeeded in carrying out the experiment.
(4)It＋特殊动词(seem，appear，happen，matter)＋that从句
☞It happened to me that I had been away when he called.
☞It is certain that she will succeed.
注意：(1)在＂It is necessary/important/strange/natural...＋that从句＂结构中，从句谓语常用＂(should＋)动词原形＂形式。
【拓展延伸】主语从句的引导词
引导词
作用
引导词
作用
that
无词义，在从句中不充当成分，但不能省略
how
多么，怎样，作方式状语或程度状语
who
谁，作主语、宾语
when
何时，作时间状语
whom
谁，作宾语
where
在哪儿，作地点状语
what
什么，可作主语、宾语、表语、定语
why
为什么，作原因状语
which
哪一个，哪些，作主语、宾语、定语
whether
是否
【特别注意】当作主语的句子太长时，为保持句子平衡，常用it作形式主语，而将真正的主语置后。if＂是否＂，不可直接引导主语从句(用it作形式主语时可以) 。
3. 主语从句的特殊用法
（1）主语从句与定语从句的转换
☞What is needed has been bought.
☞All that is needed has been bought.
所有需要的都被买了。
（2）几个特殊句型之间的转换
☞It is known to all that China has joined the WTO.
As is known to all, China has joined the WTO.
What is known to all is that China has joined the WTO.众所周知，中国已加入WTO。
4. 从句作主语时，句子谓语动词的单复数问题
(1)从句作主语时，谓语动词一般用单数。
That they are not going to the cinema is a big surprise to us.他们不去看电影，这使我们感到很惊讶。
(2)what引导的从向作主语，谓语动词一般用单数;若从句谓语或从句后的表语是复数形式,则谓语动词常用复数。
What she said is wrong.她所说的是错误的。
What we need are books.我们所需要的是书籍。
1. ______ the path of a county is the right one is a matter to be decided by