导图社区 英语语法主语从句
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英语语法主语从句
这是一篇英语语法主语从句的用法与讲解。对于想要学好英语的同学来说，非常的游泳，需要的朋友可以收藏下哟。
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主语从句
在句中充当主语的从句称为主语从句。英语中带有主语从句的句型可分为两类:一 是直接将主语从句放在主语的位置上；二是用it作形式主语，将真正的主语从句后移, 放在其他成分之后。当一个从句作主语时，无论主语从句在前还是在后，句中谓语动词一律用单数(what.从句作主语时，如果含有复数概念时，谓语动词可用复数形式)。下 面详细论述两种句型。
1. 主语从句位于句首，直接放在主语的位置上
当主语从句位于句首时，引导从句的连接词一律不能省略。下面按照引导主语从句 的3种连接词分述如下。
that, whether, if, because 引导的主语从句。
上述4个连词引导主语从句时，只起连接作用，在从句中不充当句子成分。
that-从句作主语时，that既不充当句子成分，本身也没有词义，只起连接作用。that-主语从句多用it作形式主语，但在正式文体中，为了强调that-从句的内容或使句子结构前后平衡，也可将从句位于句首
That mathematics is the base of other science is known to all of us.众所周知数学是其他科学的基础。
That he won the game made a tremendous stir in our country.他赢得比赛一事在我国引起巨大轰动。
That theory must go hand in hand with practice is a principle we should always keep in mind.理论必须与实践相结合是我们应该永远牢记的一项原则。
It seems unlikely that he will catch the train.他大概赶不上火车了。
It so happens that I know the man.碰巧我认识那个人。
whether-从有作主语 ——whether引导名词性从句时，可单独使用，也可与or或ornot /or no连用，意义为“是否”
Whether it will do us harm or good remains to be seen.此事对我们有害还是有利， 还有待于看一看。
Whether one can succeed depends on how hard he works. 一个人能否成功取决于他 工作努力的程度。
The idea itself is a good one, but whether it can be carried out or not depends upon circumstances.这个意见本身是个好意见，但能否实行要取决于境况。
if引导主语从句时，一般用于口语，且不能与or或or not /or no连用，不能直接位于句 首，要用it作形式主语，if-从句后置
It is doubtful if /whether they will come.他们是否会来是值得怀疑的。
because-从句作主语——在传统英语中，because是不能引导主语从句的。但在非正式文体中并不鲜见，特别是在现代英语中，because引导的主语从句己被部分作者接受并 出现在某些字典和教科书中。在引导主语从句时,because的用法与that, whether 一样, 只起连接作用，不充当句子成分。所不同的是，that和whether引导的主语从句可以用 it作形式主语，because-主语从句只能位于句首，不能用it作形式主语，且通常只用 于"Just because...doesn’t mean..."句型中，其意义为“仅仅因为…，仅仅…这一事实"
Just because he*s over sixty doesn't mean he must retire.仅仅是因为年过 60 这一点 并不意味着他一定退休。
Just because you speak English doesn't mean you can teach it.仅仅会说英语这一点 并不意味着你就能教英语。
Just because a person is highly intelligent does not mean that he uses it creatively. —1 个人智力高并不意味着他就能创造性的发挥才智。
连接代词引导主语从句
连接代词（The Conjunctive Pronoun） what, whatever, which, whichever, who, whom, whose, whoever, whomever 引导的主语从句与that和whether引导的名词性从句一样, 一律用陈述语气。所不同的是，除了起连接作用外，连接代词在从句中充当一定的句子 成分，可作主语、宾语、表语和定语。
1. what引导的主语从句
what 作连接代词时有两种意义：一是疑问代词型的what,意义为“什么，什么样 的”，引导疑问从句，表示未知信息；二是关系代词型的what,意义为“所…的事/物/ 东西（=the thing /things that /which）,所…那一点…"，引导名词性关系从句，表示己 知信息。what引导的名词性从句可在句中作主语、宾语、表语和定语，并在从句中充当 一个句子成分，可作主语、宾语、表语和定语。下面是what引导的主语从句。
（1） 疑问代词型的what引导的从句作主语时，主句中的谓动词只能用单数形式，what- 从句多位于句首。如：
What comes from the heart goes to the heart. ＜谚〉肺腑之言感人心。（what 在从句 中作主语）
What she did after that is not clear to us.那之后她做了什么事我们不清楚。（what在从句中作did的宾语）
What elements are is known to the students.学生们知道什么是元素。（what 在从句 中作are的表语）
What motive he could have had is not quite clear to us.他会有什么样的动机我们不 十分清楚。（what在从句中作motive的定语）
（2） 关系代词型的 what （ = the thing（s）that /which）引导的名词性关系从句在句中作主 语时，从句一律位于句首，不用社作形式主语。如：
What is hard is to do good all one's life and never do anything bad.难的是一辈子做 好事，而不做坏事。（what在从句中作主语）
What is done can not be undone. <谚〉事已定局，无可挽回。/覆水难收。（what在 从句中作主语）
What you get by your own labour is sweet to the taste.〈谚〉自己的劳动成果最香甜。 （what在从句中作get的宾语）
What we are doing today was not possible in the old days.今天我们所做的事在过去 是不可能的。（what在从句中作doing的宾语）
What I want to be is to be a teacher.我想当的是老师。（what在从句中作be的表语） ）
What little she said has left us much to think about.她说的短短几句话很令人深思 （what在从句中作little的定语
What few friends（ = The few friends that）I have here have been very kind to me.我 在这里的几位朋友一直对我很好。（what在从句中作few friends的定语）
【注释】
关系代词型的what引导的名词性关系从句作主语时，主句中的谓语动词通常用单 数形式，但当从句表示复数概念时，主句中的谓语动词可以用复数形式。如：
What he says and does do not agree.他言行不一致。
What they are looking for are two photos.他们正在找的是两张照片。
2. whatever引导主语从句时，其意义为“所…任何/ 一切事/东西”，相当于anything that,引导的名词性关系从句可作主语或宾语，并在从句充当一个句子成分，可作主语、 宾语和定语。下列是whatever引导的主语从句：
Whatever is worth doing at all is worth doing well.〈谚〉凡事不做则已，做就要做 好。（whatever在从句中作主语）
Whatever is begun in anger ends in shame. < 谚〉以愤怒开始，必以羞愧收场。 （whatever在从句中作主语）
Whatever we do must be in the interests of the people.我们所做的一切都必须符合人 民的利益。（whatever在从句中作do的宾语）
It's no good speaking to him; whatever you say goes in at one ear and out at the other. 对他讲是菠用的；无论你说什么他都当宜旁风。（whatever在从句中作say的 宾语）
Whatever I have is at your service.我所有的东西你可随意使用。（whatever在从句 中作have的宾语）
Whatever result we get must be checked.我们所取得的任何结果都要核查。（whatever 在从句中作result的定语）
3. which和whichever引导的主语从句
连接代词which （哪一个，哪个，哪些）引导的名词性从句可作主语、宾语和表语。 which-从句要用陈述语序，which在从句中充当一个句子成分，可作主语、宾语、表语和 定语。下列是Which引导的主语从句：
Which is the best of all those ways is uncertain.所有那些方法中哪一个最好还不能 肯定。（which在从句中作主语）
Which of the three forms a substance will take depends on the kind of substance, and on its volumes, temperatures and pressure.物质处于三态中的哪一种状态取决于物 质的种类，以及它的体积、温度和压力。（which在从句中作take的宾语）
Which design is the best must be tried in practice.哪一个设计最好必须在实践中验 证。（which在从句中作design的定语）
whichever意义为“任何哪一个”，可引导主语从句和宾语从句，并在从句中作主 语、宾语或定语。下面是whichever引导的主语从句：
Whichever of you comes in first will receive a prize.你们中任何哪一个得第一名都 会得奖。（whichever在从句中作主语）
Whichever you want is yours.你要任何哪一个都归你有。（whichever在从句中作 want的宾语）
4. who, whom, whose 和 whoever /whomever 引导的主语从句
连接代词who, whom, whose引导名词性从句可在句中作主语、宾语和表语，who （谁）在从句中作主语或表语，但在口语中也可以作宾语；whom是who的宾格形式，只 作宾语；whose是who的所属格形式，在从句中主要作定语，有时也可作主语或宾语。 下列是它们引导的主语从句：
Who cannot rule himself can never rule a state.〈谚〉不能自制者，决不能治国。 （who在从句中作主语）
Who goes to bed supperless all night tumbles and tosses.〈谚〉肚子填不饱，一夜睡不好。
Who that girl's father is is not clear to us all.那女孩的父亲是谁，我们大家都不清 楚。（who在从句中作表语）
Whom we must serve is a question of vital importance.为谁服务是一个极为重要的 问题。（whom在从句中花serve的宾语）
Whose carelessness spoilt the work must be made clear.由于谁的粗心破坏了工作必 须査清楚。（whose在从句中作carelessness的定语）
Whose fault it is is quite clear now.这是谁的过错现在已十分明了。 （whose在从句 中作fault的定语）
whoever /whomever （ = anybody who任何…的人）是关系代词型的连接代词，引 导名词性关系从句，作主语或宾语。whoever在从句中作主语，在口语中也可 作宾语；whomever在从句中作宾语。下列是它们引导的主语从句：
Whoever neglects learning in his youth loses the past and is dead fbr the future.〈谚〉 少时荒废学业者会失去过去，舞送未来。（whoever在从句中作主语）
Whoever has become notorious for fraud, even if he speaks the truth, gains no belief. 〈谚〉骗人出了名，讲真话也无人信。（whoever在从句中作主语）
Whoever you invite will be welcome.你邀请的所有人都会受到欢迎。（whoever在 从句中作宾语）
连接副词引导的主语从句
连接副词（The Conjunctive Adverb） when （什么时候），where （在什么地方，到哪 里，从哪里），why （为什么，…的原因）和 how （怎么，怎样，如何）引导的名词性从 句可在句中作主语、宾语、表语和同位语，并在从句中作状语。下列是它们引导的主语 从句：
When shell be back depends much on the weather.她何时回来主要取决于天气。
When and where the meeting will take place has not been decided yet.开会的时间和 地点还未决定。
Where we shall build the gas factory is being discussed.正在讨论建立煤气厂的地点。
Why he did it will remain a puzzle for ever.他干此事的原因将永远是个谜。
How the telephone was invented is a long story.电话是如何发明的说来话长。
How much water vapor can stay in the air depends upon the temperature of the air.空 气中的水蒸气有多少要取决于空气的温度。
2. 以it作形式主语的主语从句
述主语从句中，除了名词性关系从句外(关系代词型what, whatever, whichever, whoever引导的主语从句)，其他都可以用社作形式主语，将真正的主语从句后置。其中 以if和but (that)引导的主语从句只能用it作形式主语，不能直接位于句首。常见的这 种句型有以下7种：
1. It is + adj + 主语从句
It is quite possible that something has gone wrong with the machine.很可能机器出了 毛病。
It was quite clear that the crime had been done deliberately.十分明显这是故意犯罪。
It is imperative that he should be taken to hospital at once.必须把他立即送往医院。
If we are to learn something about our surroundings, it is natural that we should begin with the air.如果我们想了解我们环境的状况，当然应该从空气开始。
该句型中的主语从句除用that.从句外，还可以用连词whether, if,连接代词或连 接副词引导。如：
It is doubtful whether I shall go or stay.我之去留尚未确定。
It is uncertain whether his family was originally Britain or American,他的籍贯是英国 还是美国不肯定。
It is doubtful whether /if we shall be able to come.我们能否来尚未确定。
It is not clear how accurate the results are.这些结果的精确程度不清楚。
It is still open to question who is to head the group.谁领导这个小组还未决定。
It was clear enough what she meant.她的意思已够清楚了。
It is uncertain why he denied the charge.不明确他为什么否认了 指控。
这种句型中常用的形容词有：
It is apparent that...很明显：显然
It is clear that...显然；很明显；很清楚
It is evident that...显然；很明显
It is obvious that...显然；很明显
It is plain that...显然；很明显；很清楚
It is advisable that...最好…；…为好
It is desirable that...最好…；需要…；要…
It is preferable that...最好
It is appropriable that...…是合适的；…是适当的
It is available that...…是适用的；…是有效的
It is reasonable that...…是合理的；•••是适当的
It is nice that...…是太好了 ；微妙的是
It is good that...好在…；好的是…
It is satisfactory that..,令人满意的是…
It is too bad that……真是太遗憾了 ；真是太糟糕了 ；…太不幸了
It is essential that...必须…；…是必不可少的
It is imperative that...…是非常必要的/迫切需要的
It is important that..重要的是…；…是重要的
It is necessary that...有必要…；…是必要的
It is impossible that…不可能…；…是不可能的
It is (quite) likely that…(很)可能…，大概
It is (quite) possible that...(很)有可能…；…是可能的
It is probable that...也许；恐怕
It is doubtful that...值得怀疑
It is questionable that...成问题的是；…是有问题的
It is certain that...无疑；肯定的是
It is true that...的确；•••是确实的；…是真实的
It is notable that...值得注意的是
It is noteworthy that..,值得注意的是；显著的是
It is queer that...可疑的是；奇怪的是
It is strange that...真奇怪；令人奇怪的是
It is amazing that…令人惊异的是；…是令人惊异的
It is surprising that...令人吃惊的是；…是惊人的
It is disturbing that...令人不安的是；…得令人不安
It is conceivable that...可以想象
It is enough that...足以
It is natural that...自然…；自然的是…
It is worthwhile that...值得：…是值得的
【注释】
在这种句型中，“likely that..”不能改写成主语从句位于句首的句型。如：
①
It's highly likely that he will succeed.
不能改写为：That he will succeed is highly likely.
但可以改为：He's highly likely to succeed.
②
It is likely that he will do very well.
He is likely to do very well.他可能会干得很出色。
2. It is + n.+ 主语从句
It was a fearful disappointment to your mother that you didn't come yesterday.你昨 天没有来令你母亲非常失望。
It is common knowledge that water is made from hydrogen and oxygen.众所周知水 是由氢和氧构成的。
It is a truth that theory comes from practice.理论来自实践是条真理。
It's no matter that he didn't phone.他未打电话来也没有关系。
这种句型中的主语从句除that-clause外，也可以用whether连接代词或副词来引 导。如：
It is a complete mystery what caused the accident.是什么引起了这场事故完全是个谜。
It's still a question when we shall have our sports meet.什么岡候举行运动会还是个问题。
It's not my business how she chooses to live.她选择什么样的生活不关我的事。
It's no matter whether you get there early or late.你早到或晚到那里都无关紧要。
在这种句型中，常用作表语的名词有：
It is a common observation that...众所周知；通常人们注意到
It is a disappointment that...令人失望的是；•••是令人失望的
It is a fact of every day experience that...…是日 常经验
It is a fact that...童实是…
It is a general rule that...通常
It is a good thing that...…是件好事；好在…
It is a matter of common experience that...通常的经验是…
It is a mercy that...幸而…
It is a mystery to sb. that...…对某人来说是个谜
It is a pleasure that...很高兴…；…是件高兴的事
It is a question that...…是个问题
It is a pity that...…是个遗憾；遗憾的是…
It is a shame that...…是可耻的事/遗憾的事：遗憾的是…
It is a wonder that...…是个奇迹；…是件奇事
It is (a matter of) common knowledge that...…是常识；人所共知
It is common practice that...通常(的做法是)
It is good news that...…是好消息
It is no good that...…是无用的；…是没有好处的
It is no harm that...…是无害的
It's no matter that /whether 没关系 / 不要紧
It is a truth that...…是真理/事实；事实是…
It is no use that...…是无用的
It is no wonder that...难怪；无怪于
It is one's wish that...(某人)希望…
It is the case that...情况 / 事实是…
It is the belief that...相信
【注释】
在"It is no wonder that-"句型中，It is经常省略，只用“No wonder (that) 一”。如：
No wonder that he didn't want to go.难怪他不想去。
No wonder they were discontent and indignant.难怪他们不满意且愤愤不平。
3. It + is + v-ed + 主语从句
It is agreed that we all stand by Vidder.我们大家一致同意支持维德。
It is estimated that the work would take us two months.据估计我们要用两个月完成这项工作。
It is required that the machine should be maintained at regular intervals.机器需要定期 维修。
It has been pointed out that their suggestion is reasonable to a certain degree.已指出 他们的建议在某种程度上是合理的。
在这种句型中，除用that-主语从句外，还可以用连词whether,连接代词和连接副 词。如：
It has not been found out what particular properties this kind of alloy has.还未弄清楚 这种合金的特性。
It is not yet known whether they will send a delegation to the conference, but we hope they will.还不了解他们是否会派代表团来参加会议，但是我们希望他们派团来。
Has it been found out who set the record?搞没搞清楚这记录是谁创造的？
Has it been decided where we are to hold the meeting?决定了我们开会的地点了吗？
It hasn't been made clear when the new road is to be opened to traffic.还没有明确新 线路通车的时间。
It has not been announced when the plane is to take off.还没有宣布飞机起飞的时间。
常用于这种句型中的动词有：
It can be seen that…可见…；可以看出…
It can not be denied that...无可否认…
It has been calculated that...据估计…
It has been found that...己经发现…；巳证明…
It has been illustrated that...据图示…；据说明…
It has been made clear that...己明确宣布…
It has been objected that...有人反对…
It has been proved that...己证明…
It has been reviewed that...回顾了…
It has been settled that...己决定…
It has long been assumed that...很久以来人们都在设想…
It has not been checked whether...还没有检査…是否…
It has not been tried whether...还没有试验…是否…
It is accepted that...可接受的是…；人们认为…
It is alleged that...据称…
It is announced that...据称…；有人宣称…
It is arranged that...已商定…；巳安排…
It is asked that…有人问到…；人们会问…
It is asserted that...有人主张…
It is assumed that...假定…；假说…
It is believed that…大家相信…；人们相信…；据信…
It is claimed that…据称…：有人宣称…
It is considered that...人们认为…
It is decided that...已决定…
It is declared that...据宣称…
It is demonstrated that...据证明…；己证明…
It is enumerated that...列举出…
It is estimated that...据估计…；有人宣称…
It is expected that...预期…；人们希望…
It is felt that...有人感到…
It is found that...据发现…；人们发现…
It is generally agreed that...人们通常认为…
It is hoped that...希望：…是有希望的
It is hypothesized that...假设…
It is (well) known that...众所周知…；我们知道…
It is learned that...据说…；据闻…
It is mentioned that...上文提及…；据说…
It is noted that...有人指出…；人们注意到…
It is noticed that...人们注意到…；有人提出…
It is outlined that...概括地说…
It is pointed out that...有人指出…；人们指出…
It is predicted that...预计…；据估计…
It is preferred that...最好…
It is proposed that...有人提出…
It is recommended that...有人推荐…；规定…
It is regarded that...人们认为…
It is reported that...据报导…
It is reputed that...可以认为…；人们认为…
It is required that...要求…；…需要…
It is said that...据说…；有人说…
It is stated that...据说…；据称…
It is stressed that...有人强调说…
It is suggested that...有人建议…；建议…
It is supposed that...假定…；据推测…
It is thought that...有人认为…；我们认为…
It is understood that...很清楚…；不用说…
It is usually considered that...通常认为…
It is weighed that...权衡起来…；考虑到…
It may be safely said that...可以有把握地说…
It must be admitted that...必须承认…；老实说…
It must be pointed out that...必须指出…
It should be pointed out that...必须指出…
It should be realized that...必须明白…；要知道…
It was described that...据介绍…
It was noted above that...前面已指出…
It will be said that...有人会说…
It will be seen from this that...由此可见…
【注释】
在这种句型中，It is said that...和It is reported that..通常不能改写成主语从句位于 句首的句型。如:
a
据说意大利发生了大地震。
It is said that there has been a big earthquake in Italy. 不用：
That there has been a big earthquake in Italy is said.
b
据报道另一颗地球卫星已被发射进入轨道。
It has been reported that another earth satellite has been put into orbit. 不用：
That another earth satellite has been put into orbit has been reported.
4. It + vi. + 主语从句
It happened that I wasn't there that day.碰巧那天我不在那里。
It chanced that there were a lot of tourists in the park.正好公园里有许多游客。
It seems that the new method is successful.这种新方法似乎很成功。
It appears that he won't be back until 10 o,clock,他似乎要到 10 点钟之后才能回来。
It follows that not all substances are good conductors of electricity.由此可见并非所有 的物质都是电的良导体。
It turned out that the experiment was a success.结果试验成功 了。
It goes without saying that plants can not grow without sunlight.不言而喻，没有阳 光，植物就不能生长。
It never occurred to me that you would object to our decision.我从未想到你会反对 我们的决定。
It stands to reason that only the best boy should be chosen.理所当然，只有最优秀的 孩子才能当选。
It doesn't matter what she looks like.她的外表怎么样并不重要。
常用的这类不及物动词有：
It appears that...看来…；似乎…
It seems that...看来…；似乎…
It chanced that...恰好…；碰巧…
It happens /happened that...恰好…；碰巧…
It follows that...由此可见…
It goes without saying that...不言而喻…；毫无疑义…；不容置疑…；没有…也行
It occurs to someone that...（某人）想到…
It stands to reason that...显然…；理所当然…
It (has) turned out that...结果是…
It doesn’t matter whether...…没有关系
【注释】
1||| 本句型通常不能改为主语从句位于句首的句型。
2||| 由happen /chance, seem /appear, tum out引导的句子可以改写成"主语+ happen / chance +动词不定式”句型 如：
a
It happened that he was out of New York at the time.
He happened to be out of New York at the time.
当时屈恰好不在纽约。
b
It chanced that he was out when she called.
He chanced to be out when she called.
她来访时，他恰好外出了。
c
It seemed that something was wrong with him.
Something seemed to be wrong with him.
似乎他出了什么事。
d
It appears that you have travelled a lot.
You appear to have travelled a lot.
似乎你旅行过许多地方。
e
It turned out that the letter was a forgery.
The letter turned out to be a forgery.
结果那封信是伪造的。
由happen和chance引导的句子，还可以改写成by chance句型。如：
a
It chanced that she met him in the park.
She chanced to meet him in the park.
She met him by chance in the park.
她碰巧在公园里遇见他。
b
Do you happen to know where he is?
Do you by chance know where he is?
你恰好知道他的住址吗？
3||| “It goes without saying that-从句"可以转换成4种句型。如：
It goes without saying that health is above wealth.不用说，健康重于财富。
=It is quite obvious that health is above wealth.
=It need not be said that health is above wealth.
=It is needless to say that health is above wealth.
=Needless to say, health is above wealth.
4||| 有的语法家把"It may be that.../It is that..."也列入本类句型。在这里，be是 不及物动词，相当于to exist。如：
It may be that something has gone wrong with the machine,可能是机器出了 毛病。
Could it be that they had no place to go?他们没有地方可去，这有可能吗？
Why is it that none of them has shown up yet?怎么回事他们一个也没有来？
5. It + vt.+obj. +主语从句
这种句型主要用于"It makes no difference /odds + 主语从句”、"It doesn't make any / much /the least /a bit of difference + 主语从句”与"It makes no matter + 主语从句"句型市, 意义为“无差别，无关系，无影响"。如：
It evidently made no difference whether I was there to look after things or not.显然我 在不在那里照看东西无关紧要。
It makes no difference to me when we shall hold the meeting.我们什么时候开会，对 我都一样，
It doesn't make much /any /the least difference to me what you do.你做什么事跟我没有多大/任何/ 一点关系。
It won't make much difference whether you go today or tomorrow.你今天去还是明 天去都没有多太关系。
It makes no odds whether she goes or stays,她是走还是留都没有关系。
What odds does it make whether we go now or later?我们现在走还是以后走会有什 么差别呢？
It makes no matter whether you arrive first or last 一 there's enough food for everyone whatever time they arrive.你来早来晚都没有关系——不管什么时候来，大家都有足够的东西吃。
6. It is+(作表语的)介词短语+主语从句
It is of great importance whether we can improve our scientific research or not.我们 能否提高我们的科学研究是极为重要的。
It's of no matter to me what you do.你做什么事跟我没有关系。
It is without saying that nuclear energy will be more and more used.毫无疑问，核能 将会得到越来越广泛的应用。
7. but (that)引导的主语从句
but (that)用作从属连词引导的主语从句要用it作形式主语，将but-从句后置，且 只用于以下两种句型：
but (that) = that...not时，主句一定是否定或疑问句
It was impossible but she should see him.她不可能没有看见他。(=It was impossible that she should not see him.)
How is it possible but that we should be discontented?我们怎么可能会感到满意呢
but = that 时，通常以 odds, ten to one , a thousand to one 等词语作表语
It is odds /ten to one but you will lose.十有八九你要输。
It is a thousand to one but you'll succeed.你成功的机会只有千分之一。/你几乎失 败定了。
有时but-从句用于下列句型：
It is not impossible but such a day may come.这样的日子不是不可能到来的。