名詞性從句講解

1、 名詞性從句在句子中起名詞作用的句子叫名詞性從句 (Noun Clauses）。 名詞性從句的功能相當于名詞詞組, 它在復合句中能擔任主語、賓語、表語、同位語，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、引導名詞性從句的連接詞引導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任何成分連接代詞：what, whatever, who, whoever, whom,whose, which.wh

2、ichever,whomever連接副詞：when, where, how, why不可省略的連詞：引導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引導主語從句并在句首2. 引導表語從句3. whether從句作介詞賓語4. 從句后有"or not"Whether he will come

3、 is not clear.大部分連接詞引導的主語從句都可以置于句末，用 it充當形式主語。It is not important who will go.It is still unknown which team will win the match.二. 主語從句作句子主語的從句叫主語從句。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，在從句中充當從句的成分。例如：What he wants to tell us is not clear.Who will win the match is still unknown.It is know

4、n to us how he became a writer. Where the English evening will be held has not yet been announced.有時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 + 動詞的過去分詞 + that從句（4）It + 不及物動詞 + that 從句三、賓語從句1. 由連接詞that引導的賓語從句由連接詞

5、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，但如從句是并列句時,第二個分句前的that不可省。例如：We must never think (that) we are good in everything while others are good in nothing. He told me (that) he had finished his homework and that he wanted to go home. 2. 用who，whom, which, whose, what, when, where, why, how, whoever

6、, whatever, whichever等關聯(lián)詞引導的賓語從句相當于特殊疑問句，應注意句子語序要用陳述語序。例如：I want to know what he has told you. She always thinks of how she can work well.She will give whoever needs help a warm support. 3.此外，whether與if 在作“是否”的意思講時在下列情況下一般只能用whether，不用if：a. 引導主語從句并在句首時；b. 引導表語從句時；c . 引導從句作介詞賓語時；d. 后緊跟“or not”時；e. 后接

7、動詞不定式時。例如：Whether there is life on the moon is an interesting question. Everything depends on whether we have enough money. We didnt know whether or not she was ready.Can you tell me whether to go or to stay? 4. 注意賓語從句中的時態(tài)呼應，當主句動詞是現(xiàn)在時，從句根據(jù)自身的句子情況，而使用不同時態(tài)。例如：I know he studies English every day. （從句用一

8、般現(xiàn)在時）I know he studied English last term. （從句用一般過去時）I know (that) he will study English next year. （從句用一般將來時）I know he has studied English since 1998. （從句用現(xiàn)在完成時）當主句動詞是過去時態(tài)，從句則要用相應的過去時態(tài)，如一般過去時，過去進行時，過去將來時,過去完成時；當從句表示的是客觀真理，科學原理，自然現(xiàn)象，則從句仍用現(xiàn)在時態(tài)。例如：The teacher told us that Tom had left us for America5.

9、think, believe, imagine, suppose等等動詞引起的否定性賓語從句中，要把上述主句中的動詞變?yōu)榉穸ㄊ?。即將從句中的否定形式移到主句中。例如：We dont think you are here. 我們認為你不在這。I dont believe he will do so. 我相信他不會這樣做。四、表語從句The fact is that we have lost the game. Thats just what I want. This is where our problem lies. That is why he didnt come to the meeti

10、ng. It looks as if it is going to rain. 需要注意的，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 .五. 同位語從句同位語從句說明其前面的名詞的具體內容。同位語從句通常由that引導，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.I have no idea when he will come back home. The thought came to him that Mary had probably fallen ill. 六、名詞性that-從句由從屬連詞that引導的從句。That只起連接主句和從句的作用，在從句中不擔任任何成分，本身也沒有詞義。John s