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名词性从句与主语从句在英语语法中，名词性从句和主语从句是重要的从句类型。
它们都属于从属从句，扮演着整个句子的一个成分。
本文将详细介绍名词性从句和主语从句的定义、特点和用法，并举例说明其在实际应用中的运用。
一、名词性从句的定义和特点1. 定义：名词性从句是指在复合句中充当名词成分的从句。
它可以充当主语、宾语、表语和同位语等。
2. 特点：a. 通常由连词that, whether/if, who, whom, which, what, when, where, why, how等引导；b. 在从句中担任名词的职能，整个从句作为整体在句中起到名词的作用；c. 可以替换为一个单词或短语，使句子更加简洁明了；d. 名词性从句的引导词根据从句所充当的成分来选择。
二、名词性从句的用法名词性从句的常见用法包括主语从句、宾语从句、表语从句和同位语从句。
下面将分别进行讲解。
1. 主语从句主语从句在句子中充当主语的角色，常以that, whether/if, who, whom, which, what, when, where, why, how等引导。
例如： - Whether we can finish the project on time is still uncertain.- That he stole the money is beyond doubt.- How to solve this problem remains a challenge.2. 宾语从句宾语从句在句子中充当宾语的角色，常以that, whether/if, who, whom, which, what, when, where, why, how等引导。
例如： - She asked me where I had been all day.- I don't know if he will come to the party.- We should consider whether this plan is feasible.3. 表语从句表语从句在句子中充当表语的角色，常以that, whether/if, who, whom, which, what, when, where, why, how等引导。
第05讲名词性从句之主语从句1．了解主语从句的概念和用法。
2．可以根据本节课的内容来完成一些习题。
关于各种从句，有一个浅显易懂的规律：它在句子里面是什么成分，就是什么从句。
比如：▼ 定语从句：作定语的从句I have a dog that is very cute. 我有一只可爱的狗主语谓语宾语定语从句（句中做定语，限定修饰前面的名词dog）▼ 宾语从句：作宾语的从句，放在动词或介词后面I think the dog is very cute.我觉得这个狗很可爱主语谓语宾语从句（句中做think的宾语）▼ 状语从句：作状语的从句I bought a dog because it’s very cute. 我买了一只狗，因为它很可爱主语谓语宾语状语语从句（句中做状语，表原因）那么，主语从句是？聪明的人都能看出来——作主语的呗主语从句结构及用法在句子中担当主语的从句就叫做主语从句，通常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。
通常结构为“引导词+ 主语+ 谓语+ 其他成分"。
一. 概念：在句子中担当主语的从句就叫做主语从句，通常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。
主语从句使用陈述语序，其通常结构为“引导词+ 主语+ 谓语+ 其他成分", 但当连接代词同时充当从句主语时，其结构为“连接代词+ 谓语+ 其他成分”。
二. 引导词：引导主语从句的词有连词：that, whether, if；连接代词：what, whatever, who, whoever, whom, whomever, whose, which, whichever；连接副词：when, whenever, where, wherever, how, however, why。
答案第1页，共15页1. 连词that, whether, if引导的主语从句that在主语从句中不作成分，没有意思，不能省略；whether和if虽不作句子的成分，但有“是否”的意思，且if引导的主语从句不能位于句首。
名词性从句名词性从句〔主语、表语、宾语、同位语从句〕（一）主语从句1．定义：用作主语的从句叫做主语从句。
2．构成：关联词+简单句3．引导主语从句的关联词有三类：(1) 附属连词that。
如：That they were in truth sisters was clear from the facial resemblance between them.很明显，她们确是亲姐妹，她们的脸型很相似。
(2) 附属连词whether。
如：Whether he’ll come here isn’t clear. 他是否会来这里还不清楚。
(3) 连接代词who, whom, whose, what, which, whoever, whatever, whichever连接副词where, when, how, why。
如：What she did is not yet known. 她干了什么尚不清楚。
解释：1．主语从句能用it作形式上的主语。
常以it作形式主语的句型有：A. It+be+形容词(obvious, true, natural, surprising, good, wonderful, funny, possible, likely, certain, probable, etc.)+that从句。
如：It is certain that she will do well in her exam. 毫无疑问她考试成绩会很好。
B. It+be+名词词组(no wonder, an honour, a good thing, a pity, no surprise, etc.)+that从句。
如：It’s a pity that we can’t go. 很遗憾我们不能去。
C.It+seem, happen等不及物动词及短语+that从句。
如：It seems that Alice is not coming to the party at all. Alice似乎不来参加晚会。
主语从句导入：观察并指出句子成分A tree has fallen across the road.You are a student.To find your way can be a problem.Smoking is bad for you.一．概念：主语：主语是指句子谈论的主题，说明的人或事物。
也就是句中动作、行为、性质和状态的主体，一般位于句首主语从句：在句中充当主语的从句二·基本结构关系词简单句谓语动词宾语同位语That he finished writing the composition in such a short time surprised us all.他在很短的时间内写完作文让我们都很惊讶三关系词(引导词)1．从属连词：that whetherthat 引导主语从句只起引导作用，本身无实际意义，在主语从句中不充当任何成分，但不能省略。
That she left him cut him to the heart.That he will come is certain.注意：有时为了使句子结构平衡, 避免“头重脚轻”, 常用it 作形式主语, 而把从句放在后面。
E.gThat she has made such a mistake is a pity.It is a pity that she has made such a mistake.这样就构成了下面一些常用句型:1) It is + adj. +从句It is necessary that… 有必要…It is important that …. 重要的是…It is obvious that…… 很明显……2) It +不及物动词+从句It seems/appears that... 似乎……It happened that... 碰巧……It occurred to me that…… 我突然想起……3) It + be +过去分词+从句It is known to all that... 众所周知……It is reported that... 据报道……It is believed that... 据信……;人们相信……It is suggested that... 有人建议……It must be pointed out that... 必须指出……It has been proved that... 已证明…….4) It is + n. +从句It is common knowledge t hat… …是常识It is a surprise that …. 令人惊奇的是…It is a fact that……事实是……由whether及其他连词引导的主语从句放在句首，句后都可。
名词性从句主语从句主语从句导入：观察并指出句子成分A tree has fallen across the road.You are a student.To find your way can be a problem.Smoking is bad for you.一．概念：主语：主语是指句子谈论的主题，说明的人或事物。
也就是句中动作、行为、性质和状态的主体，一般位于句首主语从句：在句中充当主语的从句二·基本结构关系词简单句谓语动词宾语同位语That he finished writing the composition in such a short time surprised us all.他在很短的时间内写完作文让我们都很惊讶三关系词(引导词)1．从属连词：that whetherthat 引导主语从句只起引导作用，本身无实际意义，在主语从句中不充当任何成分，但不能省略。
That she left him cut him to the heart.That he will come is certain.注意：有时为了使句子结构平衡, 避免“头重脚轻”, 常用 it 作形式主语, 而把从句放在后面。
E.gThat she has made such a mistake is a pity.It is a pity that she has made such a mistake.这样就构成了下面一些常用句型:1) It is + adj. +从句It is necessary that… 有必要…It is important that …. 重要的是…It is obvious that…… 很明显……2) It +不及物动词+从句It seems/appears that... 似乎……It happened that... 碰巧……It occurred to me that…… 我突然想起……3) It + be +过去分词+从句It is said that... 据说……It is known to all that... 众所周知……It is reported that... 据报道……It is believed that... 据信……;人们相信……It is suggested that... 有人建议……It must be pointed out that... 必须指出……It has been proved that... 已证明…….4) It is + n. +从句It is common knowledge that… …是常识It is a surprise that …. 令人惊奇的是…It is a fact that……事实是……由whether及其他连词引导的主语从句放在句首，句后都可。
Whether it will please them is hard to say.It is hard to say whether it will please them.2.连接代词：who whoever whom whose what whatever which whichever What seems easy to some people seems difficult to others.Which side will win is not clear.注意：what 与that 在引导主语从句时的区别what 引导主语从句时在从句中充当句子成分, 如主语、宾语、表语, that 则不充当任何成分无意义。
例如：What you said yesterday is right.That she is still alive is a consolation1一个句子作主语时，主句的谓语动词应为单数。
Eg Whether he will come depends on the weather.2 what 引导的句子作主语时，谓语动词的数由句子的内容决定（即由表语决定)。
What I want is money.What we need are good booksWhat he said is reasonable.What we will do hasn’t been decided.3 Where he was born and where he lives now are not clear.Where and when he was born remains a secret.两个或两个以上的主从联合做主语，主句谓语动词应为复数。
两个或两个以上的连词引导一个从句，主句谓语动词应为单数。
4 Whether he will come isn’t clear. (不能换成if)It isn't clear whether /if he will come. (可以与if进行替换)（if不能置于句首）5. It 作形式主语和it引导强调句的比较①主语从句常用it作形式主语，一般常用句型为：It is+{名词/形容词/过去分词}+主语从句例如：It is still a question whether she will come or not.It is strange that you should like him.It is still unknown which team will win the match.另外，还有一些比较多见的结构：It turned out that……;It has been proved that……;It happened/occurred that……;It is well-known that……等等②而强调句则不同，它的结构是：It+be+被强调部分+that+从句强调主语：It is the times that produce their heroes.时势造英雄强调宾语：It is English that Prof.Lin teaches us.强调状语：It was in shanghai that I saw the film.判断是否是强调句有一个方法，就是将that以后的“句子的其余部分”拿出来单独看，看有没有缺成分，缺的是什么成分，再把谓语动词后面that前面的那部分，带到你认为缺成分的地方，如果放进去是一句完整的句子了，那就说明是强调句。
6. 用于It is important / natural / necessary / impossible that...句型中, 主语从句应使用虚拟语气, 谓语动词用\“should + 动词原形\”的形式, should有时有感情色彩。
It be suggested/ advised/ ordered/requested that sb (should) do sth…主语从句练习题一．翻译1．(谁将去接他)_______________________________________________ is not decided. 2．(哪个班极会赢得这场足球赛)__________________________________ is not clear .3．(他能否买到飞机票)______________________________________ doesn’t matter much. 4．(我们如何去那里)__________________________________________ is a question. 5．(你刚才告诉我的)_______________________________________ was really a surprise. 6．(他什么时候出国)_______________________________________ is being discussed 7．(他为什么哭)___________________________________________ is not clear.8．It is clear______________________________________________(他是一个乞丐). 9．(你要请谁)______________________________________________ is not important. 10．(我们将在哪里举行篮球赛)____________________________________ is not clear.二．找出下列句子中的主语从句及其引导词，并指出引导词是否充当成分，充当什么成分。
1. That we shall be late is certain.2. That the driver could not control his car was obvious.3. It is certain that we shall be late.4. It was obvious that the driver could not control his car.5. Is it possible that they will come tomorrow？6. It is clear that he was telling the truth.7. It’s probable that we’ll be a little late.8. What caused the accident is a complete mystery.9. It worried her a bit that her hair was turning grey.10. It shocked me that Peter didn’t tell anybody where he was.11. Who was responsible for the accident is not yet clear.12. It’s a pity that you can’t go with us.13. What he did is not yet known.14. It is said that he has been there many times.15. It is not yet clear who was responsible for the accident.16. When they will have the sports meet is still a question.17. It seems that he has lost something.18. What he said at the meeting encouraged everyone.19. What caused the accident was a broken bottle.20. It remains a problem whether it is true.21. Whoever breaks the law is sure to be punished.22. What she looks like doesn’t matter.23. How this happened is not clear to anyone.24. Whoever comes is welcome.25. Whether he’ll come here isn’t clear.三．用适当的引导词填空。
