高中英语主语从句全面讲解语法——Noun clauses as the subject主语从句如果一个句子在复合句中充当一个主语, 那么这个句子就是主语从句。

①That he finished writing the composition in such a short time surprised us all.②What we need are good doctors.③Whom we must study for is a question of great importance.1.主语从句的连接词1).连接词: that, whether①.That he will win is certain.②.Whether he’ll join us in the discussion is of great importance.2).连接代词: who, what, which, whom , whose, whoever, whatever, whichever①.It is clear who is afraid of having a change in land ownership.②.What India needs is a law to make land ownership fairer.3).连接副词: when, where, why, how, how many, how much , how long, how soon, how often①When we’ll start tomorrow will be told soon.②Where we can buy oxen is something we need to find out.③Why he came here is not known.④How we can protect the grain from damp needs to be discussed.【连接词】1. that——2. whether——3. who ——4. what——5. which——6. when, where ——7. why, how——8. whoever、whatever、whichever可引导主语从句。

【小结】1. 引导主语从句连词有that, whether, who, what, whatever等。

2. 连词位于句首不能省略。

3. 主语从句大多数情况下视为第三人称单数, 但在连接代词what引导的主语从句后谓语动词的数要根据句意而定。

★为了防止句子头重脚轻，通常把形式主语it 放在主语位置，真正主语后置。

1. It is certain2. It is true3. It is very likely4. It is strange5. It is a pity6. It is still a mystery7. It is said 8. It seems【小结】1.以that 引出的主语从句,常以形式主语it引导, 结构为：It is +形容词/名词/某些动词ed + that 从句。

2.在有些that从句中要用虚拟语气 (should +do/should +have done)。

★用it 作形式主语的结构(1) It is ＋名词＋从句It is a fact that … 事实是…It is an honor that …非常荣幸It is common knowledge that …是常识(2) It is ＋形容词＋从句It is natural that… 很自然…It is strange that… 奇怪的是…(3) It ＋不及物动词＋从句It seems that… 似乎…It happened that… 碰巧…It appears that… 似乎…(4) It ＋be+ 过去分词＋从句It is reported that… 据报道…It has been proved that… 已证实…It is said that… 据说…★“It” 作形式主语代替主语从句的常见句型举例①It’s + adj. + that / wh- clausee.g. It’s clear / natural / certain that clauseIt’s obvious that money doesn’t grow on trees.②It’s + p.p. + that / wh- clausee.g. It’s said / reported / known that clauseIt’s believed that he will come next week.③It ‘s + n. + that / wh- clause e.g. It’s a shame / an honour / good news that clauseIt’s still a question when we’ll have our meeting.④It + v. (n. / pron.) that /wh- clausee.g. It made us very happy that she was chosen. It appears that he forgot to sign the letter.★whether与if均为“是否”，但下列情况下只用whether ：1. 引导主语从句并在句首——2. 引导表语从句——The question is3. whether从句作介词宾语——I’m not sure about4. 引导让步状语从句时——’ll have to do it.【注意事项】1. 主语从句位于句首时必须由连接词引导。

2. 主语从句后置时引导词that可省略。

3. 主语从句位于句首时,不能用if 引导。

4. 主语从句后置时, 可以用if引导。

练一练1. makes this shop different is that it offers more personal services.2. These wild flowers are so special I would do I can to save them.3. in the regulations that you should not tell people the passport of your e-mail account.4. It is pretty well understood5. made the school proud wasmore than 90% of the students had been admitted to key universities.6. It now appears they are in need of help.7.8. It is good news they will arrive in a few days.Use the words below to fill in the blanks1. ______ watch was lost is unknown.2. ________ you did is right.3. _________ we will go for an outing tomorrow remains unknown.4. ______ we need is time.5. ______ will be our monitor hasn't been decided yet.whether what who whose whatever.WhetherWhatWhateverWhoseWho上面的空大家都填对了吗?上面每个句子都出现了的主语从句，大家能找到吗？1. Whose watch was lost is unknown.2. Whatever you did is right.3. Whether we will go for an outingtomorrow remains unknown.4. What we need is time.5. Who will be our monitor hasn't beendecided yet.1. Whose watch was lost is unknown.2. Whatever you did is right.3. Whether we will go for an outingtomorrow remains unknown.4. What we need is time.5. Who will be our monitor hasn't been decided yet.2. 在有些that从句中要用虚拟语气(should +do/should +have done)。

他出生在何地还不知道。

2. 谁会赢得比赛还不知道。

3. 谁来都欢迎。

4. 那个人为什么被谋杀尚不知道。

Where he was born has not been found.Why the person was murdered is still unknown.Who will win the match is still unknown.Whoever comes is welcome.5. What the teacher said today was quite right.老师今天说的话是十分正确的。

6. That they are badly in need of help is quite clear.他们急需帮助，这是十分明显的。

7. Whether they will sell the house is not yet decided.他们是否卖掉这所房子还没有决定。

8. Whatever was said here must be kept secret.这里说的话都应当保密。

9. Whoever makes mistakes must correct them.凡犯了错误的人都必须改正。

10. It is a pity that she has made such a mistake.她犯了这样一个错误, 真是遗憾。

11. It is believed that at least a score of buildings were damaged or destroyed.据信, 至少有二十座楼房遭到破坏或彻底毁掉。