名詞性從句的用法
在句子中起名詞作用的句子叫名詞從句 (Noun Clauses)。 名詞從句的功能相當(dāng)于名詞詞組, 它在復(fù)合句中能擔(dān)任主語、賓語、表語、同位語、介詞賓語等,因此根據(jù)它在句中不同的語法功能,名詞從句又可分別稱為主語從句、賓語從句、表語從句和同位語從句。
一、引導(dǎo)名詞性從句的連接詞
引導(dǎo)名詞性從句的連接詞可分為三類:連詞:that(無任何詞意);whether, if(均表示“是否”表明從句內(nèi)容的不確定性);as if ,as though(均表示“好像”,“似乎”)。
以上在從句中均不充當(dāng)任何成分
連接代詞:what, whatever, who, whoever, whom, whose, which. Whichever, whomever
連接副詞:when, where, how, why
不可省略的連詞:
1. 介詞后的連詞
2. 引導(dǎo)主語從句和同位語從句的連詞不可省略。
That she was chosen made us very happy.
We heard the news that our team had won.
比較:
Whether與if 均為"是否"的意思。 但在下列情況下,whether 不能被if 取代:
1. Whether引導(dǎo)主語從句并在句首;
2. 引導(dǎo)表語從句
3. Whether從句作介詞賓語;
4. 從句后有"or not"
Whether he will come is not clear.
大部分連接詞引導(dǎo)的主語從句都可以置于句末,用 it充當(dāng)形式主語。
It is not important who will go.
It is still unknown which team will win the match.
二、具體分類
1.主語從句
作句子主語的從句叫主語從句。主語從句通常由從屬連詞that,whether,if和連接代詞what,who,which,whatever,whoever以及連接副詞how,when,where,why等詞引導(dǎo)。that在句中無詞義,只起連接作用;連接代詞和連接副詞在句中既保留自己的疑問含義、又起連接作用,在從句中充當(dāng)從句的成分。例如:
What he wants to tell us is not clear. 他要跟我們說什么,還不清楚。
Who will win the match is still unknown. 誰能贏得這場比賽還不得而知。
It is known to us how he became a writer. 我們都知道他是如何成為一名作家的。
Where the English evening will be held has not yet been announced. 英語晚會(huì)將在哪里舉行,還沒有宣布。
【典例1】(2009·上海卷)It is immediately clear ____ the financial crisis will soon be over.
A. since B. what C. when D. whether
【答案】D
【解析】考查主語從句的用法。該句的意思時(shí):經(jīng)濟(jì)危機(jī)是否會(huì)很快結(jié)束是很明顯的事情。“是否”用whether表示,不能選when是因?yàn)閺木渲杏蓅oon這一實(shí)踐狀語。
【典例2】(2008·山東卷)_____ was most important to her, she told me, was her family.
A. It B. This C. What D. As
【答案】C
【解析】she told me是插入語,可刪除。what引導(dǎo)主語從句,在從句中充當(dāng)主語。
有時(shí)為避免句子頭重腳輕,常用形式主語it代替主語從句作形式主語放于句首,而把主語從句置于句末。主語從句后的謂語動(dòng)詞一般用單數(shù)形式。常用句型如下:
(1)It + be + 名詞 + that從句
(2)It + be + 形容詞 + that從句
(3)It + be + 動(dòng)詞的過去分詞 + that從句
(4)It + 不及物動(dòng)詞 + that 從句
另注意在主語從句中用來表示驚奇、不相信、惋惜、理應(yīng)如此等語氣時(shí),謂語動(dòng)詞要用虛擬語氣“(should) +do”,常用的句型有:
It is necessary (important, natural, strange, etc.) that …
It is a pity (a shame, no wonder, etc.) that…
It is suggested (requested, proposed, desired, etc.) that…
【典例】(2009·天津卷)It is obvious to the students ______ they should get well prepared for their future.
A. as B. which C. whether D. that
【答案】D
【解析】考查名詞性從句。本空格處應(yīng)是一個(gè)主語從句的引導(dǎo)詞,因該主語從句不缺成分,且句意完整,故應(yīng)用不作任何成分的連詞that。
2.賓語從句
名詞句用作賓語的從句叫賓語從句。引導(dǎo)賓語從句的關(guān)聯(lián)詞與引導(dǎo)主語從句表語從句的關(guān)聯(lián)詞大致一樣,在句中可以作謂語動(dòng)詞或介詞及非謂語動(dòng)詞的賓語。
(1) 由連接詞that引導(dǎo)的賓語從句
由連接詞that引導(dǎo)賓語從句時(shí),that在句中不擔(dān)任任何成分,在口語或非正式的文體中常被省去,但如從句是并列句時(shí),第二個(gè)分句前的that不可省。例如:
He has told me that he will go to Shanghai tomorrow. 他已經(jīng)告訴我他明天要去上海。
We must never think (that) we are good in everything while others are good in nothing. 我們決不能認(rèn)為自己什么都好,別人什么都不好。
注意:在demand,order,suggest,decide,insist,desire,request,command等表示要求、命令、建議、決定等意義的動(dòng)詞后,賓語從句常用“(should)+ 動(dòng)詞原形”。例如:
I insist that she (should) do her work alone. 我堅(jiān)持要她自己工作。
The commander ordered that troops (should) set off at once. 司令員命令部隊(duì)馬上出發(fā)。
(2)用who,whom, which, whose, what, when, where, why, how, whoever, whatever, whichever等關(guān)聯(lián)詞引導(dǎo)的賓語從句相當(dāng)于特殊疑問句,應(yīng)注意句子語序要用陳述語序。例如:
I want to know what he has told you. 我想知道他告訴了你什么。
She always thinks of how she can work well. 她總是在想怎樣能把工作做好。
She will give whoever needs help a warm support. 凡需要幫助的人,她都會(huì)給予熱情的支持。
【典例1】(2008·北京卷)The companies are working together to create _______ they hope will be the best means of transport in the 21st century.
A. which B. that C. what D. who
【答案】C
【解析】create后為賓語從句,從句中they hope是插入語,可刪除。因?yàn)閺木渲腥鄙僦髡Z,所以用what引導(dǎo)該從句。
【典例2】(2009· 全國卷Ⅰ) Could I speak to is in charge of International Sales please?
A. who B. what C. whoever D. whatever
【答案】C
【解析】 考查名詞性從句。題干中介詞to后面為賓語從句,從句中缺少主語,因此填whoever。
(3)用whether或if引導(dǎo)的賓語從句,其主語和謂語的順序也不能顛倒,仍保持陳述句語序。此外,whether與if 在作“是否”的意思講時(shí)在下列情況下一般只能用whether,不用if:
a. 引導(dǎo)主語從句并在句首時(shí);b. 引導(dǎo)表語從句時(shí);c . 引導(dǎo)從句作介詞賓語時(shí);d. 從句后有“or not”時(shí);e. 后接動(dòng)詞不定式時(shí)。例如:
Whether there is life on the moon is an interesting question. 月球上有沒有生命是個(gè)有趣的問題。
The question is whether she should have a low opinion of the test?
Everything depends on whether we have enough money. 一切要看我們是否有足夠的錢。
I wonder whether he will come or not. 我想知道他來還是不來。
Can you tell me whether to go or to stay? 你能否告訴我是去還是留?
(4)注意賓語從句中的時(shí)態(tài)呼應(yīng),當(dāng)主句動(dòng)詞是現(xiàn)在時(shí),從句根據(jù)自身的句子情況,而使用
不同時(shí)態(tài)。例如:
he studies English every day. (從句用一般現(xiàn)在時(shí))
he studied English last term. (從句用一般過去時(shí))
I know (that) he will study English next year. (從句用一般將來時(shí))
he has studied English since 1998. (從句用現(xiàn)在完成時(shí))
當(dāng)主句動(dòng)詞是過去時(shí)態(tài)(could, would除外),從句則要用相應(yīng)的過去時(shí)態(tài),如一般過去時(shí),過去進(jìn)行時(shí),過去將來時(shí)等;當(dāng)從句表示的是客觀真理,科學(xué)原理,自然現(xiàn)象,則從句仍用現(xiàn)在時(shí)態(tài)。例如:
The teacher told us that Tom had left us for America.
(5)think, believe, imagine, suppose等等動(dòng)詞引起的否定性賓語從句中,要把上述主句中的動(dòng)詞變?yōu)榉穸ㄊ健<磳木渲械姆穸ㄐ问揭频街骶渲?。例如?/p>
We don't think you are here. 我們認(rèn)為你不在這。
I don't believe he will do so. 我相信他不會(huì)這樣做。
3.表語從句
在句中作表語的從句叫表語從句。引導(dǎo)表語從句的關(guān)聯(lián)詞與引導(dǎo)主語從句的關(guān)聯(lián)詞大致一樣,表語從句位于連系動(dòng)詞后,有時(shí)用as if引導(dǎo)。其基本結(jié)構(gòu)為:主語 + 系動(dòng)詞 + that從句。例如:
The fact is that we have lost the game. 事實(shí)是我們已經(jīng)輸了這場比賽。
That's just what I want. 這正是我想要的。
This is where our problem lies. 這就是我們的問題所在。
That is why he didn't come to the meeting. 那就是他為什么不到會(huì)的原因。
It looks as if it is going to rain. 看上去天要下雨了。
需要注意的,當(dāng)主語是reason時(shí),表語從句要用that引導(dǎo)而不是because。例如:
The reason why he was late was that he missed the train by one minute this morning .
【點(diǎn)撥】whether 可引導(dǎo)表語從句,但與之同義的if卻通常不用于引導(dǎo)表語從句。
【典例1】 (2009·山東卷)The little girl who got lost decided to remain ________she was and wait tor her mother.
A. where B. what C. how D. who
【答案】A
【解析】remain是系動(dòng)詞,后加表語從句,由句意可知,從句缺地點(diǎn)狀語,所以選A。
【典例2】(2008·天津卷)The last time we had grat fun was _______ we were visiting the Water Park.
A. where B. how C. when D. why
【答案】C
【解析】was后為表語從句,此處when與the last time相呼應(yīng),根據(jù)句意可排除其他選項(xiàng)。
4. 同位語從句
同位語從句說明其前面的名詞的具體內(nèi)容。同位語從句通常由that引導(dǎo),可用于同位語從句的名詞有advice,demand,doubt,fact,hope,idea,information,message,news,order,problem,promise,question,request,suggestion,truth,wish,word等。例如:
The news that we won the game is exciting. 我們贏得這場比賽的消息令人激動(dòng)。
I have no idea when he will come back home. 我不知道他什么時(shí)候回來。
The thought came to him that Mary had probably fallen ill. 他想到可能瑪麗生病了。
【典例】(2009· 重慶卷) We should consider the students' request ________ the school library provide more books on popular science.
A. that B. when C. which D. where
【答案】A
【解析】考查名詞性從句。根據(jù)題意知,空格處是同位語從句的引導(dǎo)詞,修飾中心名詞request,且在句子中不充當(dāng)成分,故用that。這句話的意思是我們應(yīng)該考慮學(xué)生的這個(gè)要求,即學(xué)校圖書館應(yīng)該多提供一些大眾科學(xué)方面的書籍。
三、對(duì)比與用法
1.同位語從句和定語從句的區(qū)別:
that作為關(guān)系代詞,可以引導(dǎo)定語從句,充當(dāng)句子成分,在從句中作賓語時(shí)可以省略; that引導(dǎo)同位語從句時(shí),起連詞的作用,沒有實(shí)際意義,不充當(dāng)句子成分,一般不能省略。
試比較下面兩個(gè)例句:
I had no idea that you were here.(that引導(dǎo)同位語從句,不能省略)
Have you got the idea(that)this book gives you of life in ancient Greece?(that引導(dǎo)定語從句,作賓語,可以省略)
2.that-從句作主語通常用it作先行詞,而將that-從句置于句末。
用it作形式主語的that-從句有以下四種不同的搭配關(guān)系:
a. It + be +形容詞+ that-從句
It is necessary that… 有必要……
It is important that… 重要的是……
It is obvious that… 很明顯……
b. It + be + -ed 分詞+ that-從句
It is believed that… 人們相信……
It is known to all that… 從所周知……
It has been decided that… 已決定……
c. It + be +名詞+ that-從句
It is common knowledge that… ……是常識(shí)
It is a surprise that… 令人驚奇的是……
It is a fact that… 事實(shí)是……
d. It +不及物動(dòng)詞+ that-分句
It appears that… 似乎……
It happens that… 碰巧……
It occurred to me that… 我突然想起……
It is quite clear that the whole project is doomed to failure.
很清楚,整個(gè)計(jì)劃注定要失敗。
It's a pity that you should have to leave.
你非走不可真是件憾事。
3.否定轉(zhuǎn)移
(1) 將think, believe, suppose, expect, fancy, imagine等動(dòng)詞后面賓語從句的否定詞轉(zhuǎn)移到主句中,即主句的謂語動(dòng)詞用否定式,而從句的謂語動(dòng)詞用肯定式。
I don't think I know you. 我想我并不認(rèn)識(shí)你。
I don' t believe he will come. 我相信他不回來。
注意:若謂語動(dòng)詞為hope,賓語從句中的否定詞不能轉(zhuǎn)移。
I hope you weren't ill. 我想你沒有生病吧。
(2)將seem, appear 等后的從句的否定轉(zhuǎn)移到前面。
It doesn't seem that they know where to go.
看來他們不知道往哪去。
It doesn't appear that we'll have a sunny day tomorrow.
看來我們明天不會(huì)碰上好天氣。