在複合句中起名詞作用的從句叫做名詞性從句。名詞可以充當句子的主語、賓語、表語和同位語，因此，名詞性從句包括主語從句，賓語從句，表語從句和同位語從句。
①What was most important to her was her family.(主語從句)
②I don't know what you want to say.(賓語從句)
③The good news is that we have won the game.(表語從句)
④The news that we have won the game is true.(同位語從句)
引導名詞性從句的關聯詞：
注意：連詞that在引導名詞性從句時無詞義，不充當句子成分，只起連接作用，在主語從句、表語從句和同位語從句中不能省略，在引導賓語從句時，口語或非正式的文體中常被省去；疑問代詞、疑問副詞、縮合連接詞以及關聯短語在句中既保留自己的含義又起連接作用，在從句中充當成分。名詞性從句一般都用陳述句的語序，即使從句表達的是疑問含義。例如：
①The problem is what he has done to the little boy.
②We all don't know when he will come.
1. 主語從句
在複合句中作主語的句子叫主語從句
主語從句通常由從屬連詞that，whether 和連接代詞what, who,which,whatever, whoever以及連接副詞how,when,where, why等詞引導。例如：
①That he stole a bike was true.
②What he wants to tell us is not clear.
③Who will win the match is still unknown.
④Where the English evening will be held has not yet been announced.
⑤Whether he can pass the exam depends on whether he study hard or not.
⑥Whatever you do is none of my business.
⑦Whoever comes to our library will be welcome.
單個的主語從句作主語時，謂語動詞用單數形式。如果是兩個或兩個以上的主語從句作主語，謂語動詞則用複數形式。例如：
①Where and when he was born has not been found.
②When the person was murdered and why he was murdered are still unknown.
主語從句比較長的時候，為避免句子頭重腳輕，常用it 代替主語從句作形式主語放於句首，而把主語從句置於句末。主句的謂語動詞一般用單數形式。常用句型如下：
（1）It + be + 名詞 + 主語從句。例如：
①It is a fact that he has gone abroad.
②It is a pity that you missed the sports meeting last week.
（2）It + be + 形容詞 + 主語從句。例如：
①It is obvious that he told a lie.
②It is certain that he will win the game.
（3）It + be + 過去分詞 + 主語從句。例如：
①It is said that she will come to the party tomorrow.
②It has not been announced when the plane are to take off.
（4）It + 不及物動詞 + 主語從句。例如：
①It happened that the meeting was canceled that day.
②It occurred to me that I had forgotten to bring my wallet.
注意:在主語從句中用來表示驚奇、不相信、惋惜、理應如此等語氣時，謂語動詞要用虛擬語氣 (should) +do，常用的句型是：
It is necessary/important/natural/strange/essential, etc.) that … 例如：
①It's necessary that you should study hard.
②It is strange that he should say that.
③It is essential that a college student should master at least a foreign language.
2. 賓語從句
在複合句中作賓語的從句叫賓語從句。
引導賓語從句的關聯詞與引導主語從句表語從句的關聯詞大致一樣，在句中可以作謂語動詞或介詞及非謂語動詞的賓語。例如：
①I want to know what he has told you.
②She always thinks of how she can work well.
③She will give whoever needs help a warm support.
1).由連接詞that引導的賓語從句
由連接詞that引導賓語從句時，that在句中不擔任任何成分，在口語或非正式的文體中常被省去。但如從句是並列句時,第二個分句前的that不可省。例如：
He has told me (that) he will leave Wuhan and that he will go to Shanghai tomorrow.
注意:在insist,suggest, advise,decide, demand, desire,require, request,order, command等表示"堅持、建議、決定、要求、命令"（"堅決要命"）等意義的動詞後，賓語從句中謂語部分常用 虛擬語氣，即should+ 動詞原形。例如：
①I insist that she (should) do her work alone.
②The commander ordered that troops (should) set off at once.
但是, 如果suggest作"表明、暗示"講, insist作"堅持說、堅持認為"講，則其後的賓語從句中用陳述語氣。例如：
①The smile on his face suggested that he had passed the examination.
②The boy insisted that he had not stolen the money.
2).用whether或if引導的賓語從句
whether和if均可引導動詞後的賓語從句，常可互換。但從句中有or not時或介詞後的賓語從句中只能用whether連接。其它名詞性從句，如主語從句、表語從句、同位語從句中表示"是否"只用whether. 介詞後的賓語從句一般不用which和if引導，要用whether和what。that也很少引導介詞賓語從句，只在except, but, besides等之後才用。例如：
①I don't care about whether you have money or not.
②Everything depends on whether we have enough money.
③He seldom loses his temper except that you make a fool of him.
3).賓語從句中的時態呼應
賓語從句的謂語動詞時態受主句謂語動詞的影響，如果主句的謂語動詞是一般現在時，從句中的謂語動詞可以用各種時態。 例如：
①I know that he studies English every day.
②I know that he studied English last term.
③I know (that) he will study English next year.
④We all know that he has studied English since 1998.
如果主句中的謂語動詞用了一般過去時，則從句中的語動只能用過去時的某種形式，如一般過去時，過去進行時，過去將來時等。 例如：
①We believed that he had earned enough money to build a house.
②The teacher told us that Tom had left us for America．
當從句表示的是客觀真理，科學原理，自然現象，則從句仍用現在時態。 例如：
The teacher told us that the sun rises in the east.
4).當主句是I/ We think (suppose, expect, believe, guess, imagine) 時，其後的賓語從句如果是否定形式，常把否定詞not從從句中轉移到主句中成為否定的轉移。例如：
①We don't believe that he will win the game.
②I don't think he will do so.
注意：doubt用於肯定結構時，後面用whether/ if 引導名詞性從句；用於否定結構或疑問結構時，後面用 that 引導名詞性從句。be sure 用於肯定句或疑問句時，後接 that 引導的名詞性從句；用於否定句時，後接whether/if 引導的名詞性從句。例如：
①I doubt whether he will come tomorrow.
②There is no doubt that he will come tomorrow.
③I am sure that he will win the game.
④I am not sure whether he will win the game.
3. 表語從句
在複合句中作表語的句子叫表語從句。表語從句常放在系動詞之後。
引導表語從句的關聯詞與引導主語從句的關聯詞大致一樣，表語從句位於連繫動詞後，有時用as if, because引導。其基本結構為：主語 + 系動詞 + 表語從句 。 例如：
①The fact is that we have lost the game.
②That's just what I want.
③This is where our problem lies.
④That is why he didn't come to the meeting.
⑤It looks as if it is going to rain.
⑥This is because he missed the train by one minute.
注意：當主語是reason 時，表語從句要用that引導而不是because。例如：
The reason why he was late was that he missed the train by one minute this morning.
4. 同位語從句
在複合句中作同位語的從句叫同位語從句。同位語從句用於解釋說明其前面的名詞的具體內容。
同位語從句一般跟在某些表示抽象概念的名詞後,如 news, idea, information, fact, hope,thought, belief 等，用來說明名詞所表示的具體內容，引導同位語從句的連接詞通常有that, whether和連接副詞when, where, why, how；連接代詞who，what，whose，which也可以引導同位語從句。例如：
①The news that he won the first place was true.
②It is a question how he did it.
③The problem whether we should continue to do the experiment has been solved.
④We haven't settled the question where we are going to spend our summer vacation.
⑤I have no idea when she will be back.
⑥The question who should do the work requires consideration.
同位語從句一般緊跟在被解釋的名詞之後，但有時候也可以分開，將從句放在句末。例如：
①The suggestion came from the chairman that the new rule should be adopted.
②Word came that Mr. President would come and inspect our school.
5.同位語從句與定語從句的區別（1）定語從句修飾限定先行詞，它與先行詞是修飾關係；同位語從句解釋說明先行詞的具體內容，它與先行詞是同位關係。①The plane that has just taken off is for Paris. （定語從句） ②The fact that he has died is quite clear. （同位語從句）（2）定語從句由關係代詞或關係副詞引導，關係詞在從句中擔當相應的句子成分，關係代詞在從句中作賓語時經常可省略。同位語從句主要由連詞that 引導，在從句中不充當句子成分；where, when, how, who, whether, what 等連詞也可以引導同位語從句，這些連詞則在從句中擔當成分。①The news that he told me is true. （定語從句）
②The news that he has just died is true. （同位語從句）
③The problem that we're facing now is how we can collect so much money. (定語從句)
④The problem how we can collect so much money is hard to solve. （同位語從句）
⑤The question that he raised puzzled all of us. （定語從句）
⑥The question whether he is sure to win the game is hard to answer.（同位語從句）
（3）同位語從句與先行詞一般可以用be動詞發展成一個完整的句子, 而定語從句則不能。如：①The idea that we can ask the teacher for advice is wonderful.
（同位語從句）
→The idea is that we can ask the teacher for advice.②The fact that the earth moves around the sun is known to all. （同位語從句）→The fact is that the earth moves around the sun.③Pay attention to the problem how we can protect the wild
animals. （同位語從句） →The problem is how we can protect the wild animals.
高考英語短文改錯及語法填空分析與訓練·名詞性從句
考點規律分析:名詞性從句短文改錯改錯考點主要涉及從句引導詞的誤用、缺失以及多餘。語法填空主要涉及從句引導詞的選擇。
名詞性從句單句改錯之真題訓練：
1.…but it didn't matter that I would win or not. (全國卷)
2..(2016·全國卷Ⅰ)My uncle is the owner of a restaurant close to that I live
3.(2016·全國Ⅱ)The summer holiday is coming.My classmates and I are talking about how to do during the holiday.
4.Besides, I have few friends, I don't know that they don't like to talk with me. (全國卷)
名詞性從句單句改錯之提升訓練：
1. It's uncertain that the experiment is worth doing.
2.That is hard is to do good all one's life and never do anything bad. 3.What the boy didn't take medicine made his mother angry.
4.What he really means is what he disagrees with us.
5.If we can finish translating the book depends on the time.
6.That is that Lu Xun once lived.
7. The fact which she had not said anything surprised all of us.
8. There is no doubt whether he will come tomorrow.
9. The reason why he was late was because he missed the train by one minute this morning.
10.That he wants to tell us is not clear.
名詞性從句單句語法填空之真題訓練：
1.(2016·全國Ⅰ，閱讀B)We now realize ________ important family is and how important to be near them, especially when you're raising children.
2.(2016·全國Ⅱ，閱讀B)Members leave books on park benches and buses, in train stations and coffee shops.________ finds their book will go to the site and record where they found it.
3.(2016·全國Ⅱ，閱讀D)The journey was intended to achieve more than ________Captain Robert Falcon Scott had done.
4.(2016·北京，29)The most pleasant thing of the rainy season is________one can be entirely dust.
5.(2016·四川，七選五)Scientists are still not exactly sure ________genes influence aging, but they believe that they do.
6.(2016·江蘇，21)It is often the case________anything is possible for those who hang on to hope.
7.(2015·湖南，26)You have to know ________ you're going if you are to plan the best way of getting there.
8.(2015·北京，33)I truly believe ________ beauty comes from within.
9.(2015·重慶，8)We must find out ________ Karl is coming, so we can book a room for him.
10.(2015·四川，8)The exhibition tells us________we should do something to stop air pollution.
11.(2015·安徽，25)A ship in harbor is safe, but that's not________ships are built for.
12.(2014·大綱全國，24)Exactly ________ the potato was introduced into Europe is uncertain，but it was probably around 1565.
學習札記：
參考答案及解析
名詞性從句單句改錯之真題訓練：
1.that 改為 whether，whether 與 or not 搭配，表示"是否"
2.that－where 考查從句連詞。該句是賓語從句，意為"靠近我住的地方"，that改為where。
3.how→what 考查疑問詞的用法。我和同學們正在談論假期裡做什麼。固定表達what to do，如何用how結構為how to do sth。
4. that 改為 why，why 引導賓語從句，表示原因
名詞性從句單句改錯之提升訓練：
1.that改為whether 考查賓語從句引導詞，whether表示"是否"
2.That改為What，表示"......的事情"，引導主語從句
3.What改為that，引導主語從句，不翻譯，無實際意義.
4.第二個what改為that，引導表語從句
5.If改為whether，表示"是否"，引導主語從句
6.第二個that改為where，引導表語從句，其中where作從句的地點狀語。
7.which改為that，引導同位語從句。
8.whether改為that，There is no doubt that......意為"毫無疑問"，用that引導同位語從句。
9.because改為that，that引導表語從句。The reason why ...Is/was that...為固定句式，意為"......的原因是......"
10.That改為What，引導主語從句，表示"......的事情"
名詞性從句單句語法填空之真題訓練：
1．how [考查賓語從句的連接詞。根據後面的how important可以看出此處也是填how。]
2．whoever [考查名詞性主句中的主語從句。句意：無論是誰發現了他們的書，都去那兒，並記錄下他們是在哪兒發現的書。]
3．what [考查名詞性從句，引導詞在從句中做had done的賓語，故用what。]
4．that [考查名詞性從句。句意：雨季最令人愉快的事情是人可以完全免於塵埃。分析句子結構可知is後的表語從句中不缺少成分，且句意完整，故選D ]
5．how [句意：科學家仍然不確定基因是如何影響人的年齡的，但是他們相信會影響。用how最為貼切。]
6．that [考查主語從句的引導詞。句意：通常情況下，對於那些堅持希望的人來說，一切皆有可能。本句中的it為形式主語，真正的主語為後面的名詞性從句，從句結構完整，不缺成分也不缺意義，故要用that引導。]
7．where [句意：如果你要計劃到達某地的最佳路線，你必須首先知道你想要去哪？where引導賓語從句，在從句中用作地點狀語。]
8．that [句意：我真的相信美來自人的內心。賓語從句意思完整隻缺連接詞，故用that。]
9．when [句意：我們必須知道他什麼時候來，以便我們能給他預定房間。根據後面的so we can book a room for him可知這裡指時間，故用when引導。]
10．why [考查賓語從句。句意：這個展覽告訴了我們，我們為什麼要阻止空氣汙染。賓語從句缺少狀語，根據意義為why。]
11．what [句意：船停放在海港裡是很安全的，但這並非建造船的目的。該題考查表語從句。isn't後跟從句作表語，表語從句中的for後缺少賓語，用what引導，what與for連用，表示目的。What在句中既作連接詞又作從句的中for的賓語。]
12．when [考查名詞性從句。句意：馬鈴薯被引入歐洲的確切時間是不確定的，但是大約是在1565年。根據句意when引導一個主語從句，且在從句中作時間狀語。故填when。]
