小简老师说：
在复合句中起名词作用的从句叫作名词性从句。包括主语从句、宾语从句、表语从句和同位语从句。
注：由于名词性从句在句中不同的句法功能（即名词性从句在复合句中，能充当主语、宾语、表语、同位语等。）相应地，名词性从句可以分为主语从句、宾语从句、表语从句和同位语从句。
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类别功能例词
从属连词指起连接作用，不充当从句中的任何成分that, whether, if
连接代词既起连接作用，本身又作从句的主语、宾语、表语或定语who, whom, whose, which, what, whoever, whatever, whichever
连接副词既起连接作用，本身又作从句的状语when, where, how, why，whenever，wherever，however2:主语从句
主语从句可直接放在句首，也可用形式主语it代替，而将主语从句后置。
that引导的主语从句
1)that引导的主语从句置于句首（that此时在从句中不充当任何成分，无含义，只起连接作用，不能省略）
That the earth moves around the sun is known to all.
注：从句作主语，谓语动词用单数形式。
2)在that引导的主语从句中，常用it作形式主语，that引导的真正的主语从句后置，常见的此类句型有：
①It+系动词+形容词+that从句。
常用于这种结构的形容词有：necessary必要的certain明确的
right正确的clear清晰的
(un)likely（不）可能的possible可能的
strange奇怪的obvious明显的
natural自然的important重要的
It is likely that he can’t come to the meeting.It is obvious that you have made a big mistake.
注：It is necessary/important/surprising/strange/unthinkable/unbelievable/incredible that+主语(should)+动词原形+其它。
例：It is necessary that a college student (should) master one or two foreign languages.It is strange that you (should) trust Jane.
②It+系动词+名词+that从句。
常用于这种结构的名词有：a pity遗憾a honor荣耀
a shame令人遗憾的事a wonder奇迹
good news好消息no wonder难怪
a fact事实no surprise不奇怪
It is a pity that you didn’t attend the lecture yesterday.It is no wonder that you’ve achieved so much success.
③It+ be+过去分词+that从句。
常用于这种结构的过去分词有：said据说told有人告诉
heard有人听说reported据报道
decided作出决定suggested有人建议
advised有人建议ordered根据命令
remembered有人记得thought有人认为
considered认为well-known很著名
hoped有人希望announced据宣布
It is reported that no passengers were injured in the accident.It is generally considered that boys are better at science than girls.
注：It is suggested/advised/ordered/requested/insisted/demanded +that+主语(should)+动词原形+其它。
例：It is suggested that you(should) spend more time in studying English.
④It+动词（+宾语或状语）+that从句。
常用于这种结构的动词有：seem显得happen碰巧
matter重要occur出现
turn out结果是
It happened to me that I was away when he called.It occurred to me that we should get in touch with the manager.
whether/if引导的主语从句
whether引导的主语从句即可以放在句首，也可以放在句末，但if引导的主语从句只能放在句末，前面需用it作形式主语。whether， if只起连句中不作成分，且不可省略。
Whether you can succeed or not depends on how hard you work at it.（whether引导的主语从句放在句首）
It is unknown whether/if he has agreed to my plan.（主语从句是whether/if he has agreed to my plan, it作形式主语）
连接代词或连接副词引导的主语从句
1）连接代词what, who, whom, , whose, which , whatever, whoever, whichever等在从句中作主语、宾语、表语、定语,不可以省略。
What he said just now is true.Who breaks the law will be punished.
注：①whoever和whatever引导的名词性从句一般不用it作形式主语。②what 引导的主语从句一般按单数对待，但在实际使用中，其单复数取决于其成分的含义。
例： What the kid wanted was only a new school bag.（schoolbag是可数名词单数，谓语动词用单数）What they need are a car and some water.（a car and some water表示复数概念，谓语动词用复数）
2）连接副词when, where, why, how，whenever，however，wherever等在从句中作状语。
Why they suddenly disappeared remains a mystery.（why在从句中作原因状语）
When we’ll go for a picnic isn’t known.（when在从句中作时间状语）2:宾语从句
句法功能
1)作动词的宾语
①大多数位于及物动词后。I hope (that) you can join us in the game.I doubt whether/if he will come to the wedding.
②有些动词短语后。
常见的这类动词短语有：find out查出turn out结果是
point out指出make sure确信
figure out辨别出keep/bear in mind牢记
Please find out when the ship sails for New York.
We should keep in mind that sports can help us develop both our bodies and characters.
③可以运用it作形式宾语代替宾语从句
A.动词find, feel, think, consider, make, believe, guess, suppose, assume等后有宾语补足语时，要用it作形式宾语，而把that引导的宾语从句后置。
例：I think it necessary that we take plenty of hot water every day.I have made it rule that I keep diaries.
B.有些动词（词组）带宾语从句时需要在从句前加it.如：hate, dislike, appreciate, see to, depend on等。除此之外，take it for granted中的it是位于动词短语而不是从句前。
例：I hate it when they talk with their mouths full of food.Some students just take it granted that they will pass the exam.
2)作介词的宾语
一般情况下介词后常用wh-类连接词引导宾语从句。（有的介词如in, except, but后可跟that引导的宾语从句）
We are talking about whether we admit students into our clubs.They look similar except that one is a little tall.
3)作系表结构的宾语。
常用于此类结构的形容词有：sure, certain, glad, pleased, happy, afraid, surprised, satisfied, sorry等表示“情感”的形容词。
We’re all pleased that we have once again overcome the difficulty.I am extremely sorry that I have troubled you so much.
that引导的宾语从句
that引导的宾语从句表示陈述意义。that无实际意义，在从句中不充当任何成分。that可以省略。
I don’t think (that) there will be time to do it.Many people believe that robots will do most of our work.
whether/if引导的宾语从句
1）可用whether/if的情况
whether/if常放在ask, care, wonder, find out等后引导宾语从句。whether/if在从句中不作成分，但是有“是否”含义，不可省略。
I asked them whether/if they would win the match.Do you care whether/if you win?
2) 只用whether不用if的情况
①引导介词后的宾语从句时。
It depends on whether it will snow tomorrow.
②与or not连用时。
I asked your secretary whether she could come or not.
③与不定式连用时。
I really don’t want know whether to accept or refuse.有些动词，如leave, put, discuss, doubt等后的宾语从句常用whether引导。
④We doubt whether he will keep his promise.
⑤宾语从句前置，置于句首时。
Whether they can come here on time, we don’t know.
连接代词或连接副词引导的主语从句
1）连接代词what, who, whom, , whose, which , whatever, whoever, whichever等在从句中作主语、宾语、表语、定语,不可以省略。
I don’t know whom you should depend on.Could you tell me which gate we have to go to?
2) 连接副词when, where, why, how，whenever，however，wherever等在从句中作状语。
He didn’t tell me when the traffic accident had taken place. Could you please tell me how I can read the new world?
注：how构成的疑问短语也可以引导宾语从句，常见的有how old, how many, how much, how far, how soon, how long等。例： Do you know how old your English teacher is.
宾语从句的注意事项
1）宾语从句的时态
宾语从句谓语动词的时态常常受到主句谓语动词的影响，因而在使用时要注意主句和从句两部分的时态。
用法例句
当主句的谓语动词是一般过去，其宾语从句的时态一般要用相应的过去时态The policewoman asked the little boy where he lived.He said (that) he was going to take care of the baby.
当主句的谓语动词是一般现在时或祈使句，其宾语从句的时态可以任何适当的时态Do you know how Amy came to school this morning?Please tell me whom you went to the garden with this morning.
当宾语从句表达客观事实或规律时，其时态应用一般现在时Everyone knew that there are sixty minutes in an hour.The teacher said that the earth goes around the sun.
2) 宾语从句的语序
陈述句作宾语从句时，仍然用陈述语序；疑问句作宾语从句时，原来的倒装语序要改为陈述语序。
Tom advised that I should take more water.I don’t know why he is leaving.
宾语从句的语序：引导词+主语+谓语+其他
3) 宾语从句的否定转移 主语是第一人称I/we，主句的谓语动词是表示“想，认为”等意义的动词，如：think，believe, imagine, suppose, expect, guess等，若后面的从句时否定意义时，从句的否定一般要转移到主句中，其反义疑问句的人称和时一般要与宾语从句一致。
We don’t think you can play the guitar.I don’t believe that’s his fault, is it?We find that he seldom goes to visit his teacher, does he? （否定词否定，hardly, never, seldom, no, few, little等）
4） 不能省略that的情况
在that引导的宾语从句中，连接词that只起引导作用，无具体意义，不在从句中充当任何成分，常常可以省略。但是，在下列情况中不可以省略。
①句中出现两个或两个以上的由that引导的宾语从句时。此时，只有第一个从句中的that可以省去，其余并列的宾语从句中的that都要保留。He said (that) the film was excellent and that he wanted to see it once again.
②that从句中又有其他从句时。I am afraid that if you’ve lost it, you must pay for it.
③it作形式宾语代替that引导的宾语从句时，不能省略that。We took it for granted that they would help us.
④当宾语从句的主语是this，that或者被this，that修饰时。He said that this book was very useful.
⑤当宾语从句时双宾语中的直接宾语时。I want to tell you that this problem is very common.
⑥宾语从句前有插入语时。We hope, on the contrary, that he will stay at home with us.
⑦that引导的宾语从句谓语句首时。That our team will win, I believe.
⑧宾语从句在except, but, except, in等介词之后。He also likes playing the piano besides that he is good at playing basketball.3:表语从句
表语从句位于主句的连系动词be, seem, look, sound, taste, feel, remain, appear等之后，常用的连接词与主语从句和宾语从句的连接词相同，用法也一样。此外，表语从句还可用as if, as though, because来引导。
that, whether引导的表语从句
that, whether只起连接作用，在从句中不作成分。that无实义，一般不可省略，whether意为“是否”，不能换成if.（一般不用if引导表语从句）
Our problem is that I don’t look any different from other people.Another important difference is whether schools are state schools or private schools.
as if, as though, because引导的表语从句
1）as if, as though 引导的表语从句可用陈述语气，也可用虚拟语气。
You look as if you’ve had a good time. （陈述语气）You look as if he were from the Mars. （虚拟语气）
注：此类表语从句常跟在特定的动词后面，如seem, appear, look, taste, sound, feel等。
2）because引导的表语从句主语不能用reason。
---You look tired.---That may be because I didn’t have a good sleep yesterday morning.
注：如果主句主语是reason，表语从句的连接词用that，不能用我why或because。常见的句型为“The reason(why) is that…”。
The reason (why) he came late was that he got up late.（that不能换成because）
表语从句的注意事项
1）wh-表语从句应注意的问题
wh-类连接词引导的表语从句作表语时，通常不含疑问意义，而是分别表示具体的地点、时间、原因和方式等。
This is why I think my happiest days will be in the future. （表示具体原因）Tomorrow is when it will be most convenient. （表示具体时间）This is where I met Peter for the first time. （表示具体地点）
2）表语从句用虚拟语气的情况
如果主句的主语是advice, demand, order, suggestion, requirement, request, command等时，表语从句用虚拟语气，结构是“(should)+动词原形”。4:同位语从句
同位语从句是用以解释说明某一名词内容和实质的从句。常见的连接词有：that, whether, why, who, where, how, when等。if一般不引导同位语从句。that, whether不作成分，whether表示“是否”，其它连接词具有实义，同时在同位语从句中作一定成分。引导同位语从句的连接词一般不可省略。
常跟同位语从句的名词或短语。
belief信念with the exception…除外
explanation解释doubt怀疑
idea主意hope希望
opinion观点news消息
thought想法possibility可能性
truth事实wish愿望
question问题fact事实
problem问题promise诺言
report报道Reply答复
advice建议suggestion建议
word消息warning警告
The story goes that the lost child has gone abroad.Jim kept his promise that he would always do everything he could for Mary to make sure of her happiness.
同位语从句的注意点
1）同位语从句的语气
在suggestion, advice, request, order ,demand, requirement等意为“建议，命令，要求”的名词后，同位语从句中的谓语动词常用“should+动词原形”的虚拟语气结构，其中should可以省略。
The suggestion came from the chairman that the new rule (should) be adopted.The government gave the order that all these houses (should) be pulled down in three weeks.
同位语从句相当于一个名词，对前面的抽象名词进行解释和说明；而定语从句相当于一个形容词，对先行词进行修饰或限定。 The girls were surprised at the fact that ocean ships can sailed up the Great lakes. （同位语从句）There are laws that do not allow people to burn too much coal. (定语从句) ②从引导词上区别： 引导定语从句的that是关系代词，它的作用是连接主句和从句，并代表先行词在从句中充当成分，且that作宾语时可以省略，指物时可用which代替。而引导同位语从句的that是连词，只起连接主句和从句的作用，它不充当任何成分，不能省略，也不可被which替代。 We expressed the hope that Mr and Mrs Smith would come to China the next year. （同位语从句）The news (that/which) we heard spread all over the city.（定语从句） ③从所修饰词上区别：
同位语从句修饰的名词数量有限，往往是含有某种信息的词，如message, news, fact, hope等。而定语从句修饰的词可以是名词、代词、主句的一部分或整个主句。 Some people have the idea that you can cross Canada in less than five days. （同位语从句）The time when I first met Nelson Mandela was a very difficult period of my life. （定语从句）
凡是同位语从句，改为The fact/news/idea/order/truth is/was… 结构时，从语法和语义上都讲的通，而定语从句则不可。
The news that our team won the game excited us all.The news is that our team won the game. (√)
The news that the radio broadcast this morning is not true at all.The news was that the radio broadcast…。(×)
