Ⅰ.名詞性從句的結(jié)構(gòu)和功能：名詞性從句包括主語從句、賓語從句、表語從句、同位語從句。名詞性從句主要有四種從句結(jié)構(gòu)：以that引導(dǎo)的從句；以whether/ if引導(dǎo)的從句，以特殊疑問詞引導(dǎo)的從句；以what或wh-ever等連接代詞引導(dǎo)的名詞性關(guān)系從句。此外，as if/ as though也可引導(dǎo)表語從句。 Ⅱ.名詞性從句的連接詞：引導(dǎo)名詞性從句的連接詞有：從屬連詞、連接代詞和連接副詞。

1. 從屬連詞：that(本身無意義)，whether(是否)，if(是否)。只起連接作用，在從句中不作任何成分。
2. 連接代詞：who, whom, whose, which, what, whatever, whoever等。它們除起連接作用外，還可在從句中充當(dāng)主語、賓語、定語、表語等成分。
3. 連接副詞：when(＝the time when什么時候，何時)，where(＝the place where什么地方，何地)，how(＝the way that/in which怎樣，以……方式，如何)，why＝the reason why為什么)。它們除起連接作用，還在從句中作狀語。溫馨提示：what與that引導(dǎo)名詞性從句的區(qū)別：
4. what在名詞性從句中可充當(dāng)主語、賓語和表語，意義上相當(dāng)于the thing(s) that，引導(dǎo)主語從句時，其謂語動詞的單復(fù)數(shù)依句意而定。e.g. What the lecturer said is very valuable.We wonder what he will do next.
5. that引導(dǎo)名詞性從句不充當(dāng)任何句子成分，只起連接作用，無任何意義。引導(dǎo)主語從句時，常用it作形式主語，謂語動詞用單數(shù)，引導(dǎo)賓語從句時，常被省略。e.g. That she will refuse the offer seems unlikely.I have found (that) all the tickets have been sold out.It is a pity that you missed such a fine talk. Ⅲ.名詞性從句的分類以及用法：（一）主語從句：
6. 主語從句的基本用法：

1. that引導(dǎo)的主語從句既可放在句首，也可放在句尾，that起連接作用，無詞義，在從句中不作成分，一般不能省略。e.g. That we are invited to a concert this evening is good news to us.＝It is good news to us that we are invited to a concert this evening.
2. whether引導(dǎo)的主語從句可放在句首，也可放在句尾；if引導(dǎo)的主語從句只能放在句尾，前面需要it作形式主語。whether/ if 起連接作用，“是否”，在從句中不作成分。e.g. Whether he will go there or not is not clear.It is doubtful whether/ if the work can be completed.
3. wh-類連接詞引導(dǎo)的主語從句：wh-類連接詞包括wh-類的連接代詞(who, whom, whose, which, what, whoever, whomever, whichever, whatever等)和連接副詞(when, where, how, why, whenever, wherever, however等)。what, when和wh-ever類的詞有時可不表疑問。wh-類連接代詞在句中既起連接作用，又可充當(dāng)主語、賓語、表語、定語等成分。wh-類連接副詞在句中起連接作用，在從句中可充當(dāng)時間、地點、原因、方式狀語。

1. 主語從句的單復(fù)數(shù)問題

1. 從句作主語時，謂語動詞一般用單數(shù)。e.g. That he will come and help us is certain.Who will go to the energy conference is not important.
2. what引導(dǎo)的從句作主語，表示單數(shù)概念，謂語動詞一般用單數(shù)形式；表示復(fù)數(shù)概念，則謂語動詞常用復(fù)數(shù)。e.g. What he said is true.What he needs are books.

（二） 賓語從句：

1. 賓語從句的基本用法：

1. 動詞后接賓語從句的用法：e.g. I know that he is friendly and hospitable.Go to stamp sales and buy whatever you can afford.溫馨提示1：doubt, doubtful與sure后名詞性從句連接詞that, whether, if的選擇。①當(dāng)doubt, doubtful用于肯定句時，后面的名詞性從句的連接詞常用whether或if；當(dāng)doubt, doubtful用于否定句或疑問句時，后面名詞性從句的連接詞用that。e.g. I doubt whether/ if he is at home.We don’t doubt that they can complete the task ahead of time.It is doubtful whether it is true or not.②當(dāng)be sure用于肯定句時，后面的賓語從句的連接詞常用that；當(dāng)be sure用于否定句時，后面的賓語從句的連接詞常用whether或if。e.g. We are sure that he is innocent.The old man didn’t seem to be sure whether/ if he had met me.
2. 介詞及形容詞后接賓語從句的用法：e.g. We are talking about whether we admit students into our club.He was interested in whatever he saw there.He is pleased that he has passed a tough test.溫馨提示2：①一般情況下介詞后只能用wh-類連接詞引導(dǎo)的賓語從句。e.g. I am surprised at what he said.②介詞后如果接that從句，要先加上it，再加that從句，即“介詞＋it＋that…”結(jié)構(gòu)。e.g. You may depend on it that they will support you.③介詞except, but, besides及in后可接that從句。e.g. I know nothing about him except that he lives here.④常接賓語從句的形容詞有sure, certain, glad, pleased, happy, afraid, surprised, satisfied, sorry等。e.g. I’m afraid he won’t attend our wedding.
3. that引導(dǎo)的賓語從句：e.g. We are glad that so many old friends will attend our tea party.The headmaster said that the school reports had been sent off.溫馨提示3：在suggest, demand, order, insist等動詞之后的賓語從句中用虛擬語氣，“(should＋)動詞原形”。e.g. He suggested that we (should) set about doing the work at once.
4. whether/ if 引導(dǎo)的賓語從句：e.g. I’ll try to find out whether/ if the machine is in good condition.溫馨提示4：① whether/ if引導(dǎo)賓語從句表示“是否”的意思時，一般情況下可互換。② if引導(dǎo)賓語從句時可以有否定式，而whether從句則沒有。e.g. I don’t care if he doesn’t come.
5. 特殊疑問詞引導(dǎo)的賓語從句：由who, what, how, which, whose, where, why等詞引導(dǎo)的賓語從句，可作動詞、介詞及形容詞的賓語。e.g. I can’t imagine how he did it.We are worrying about what we should do next.I wasn’t certain whose house I was in.溫馨提示5：如果疑問詞是介詞的賓語，介詞可位于從句句首或句末。e.g. I didn’t know in which building they lived.＝I didn’t know which building they lived in.

1. 賓語從句的時態(tài):

1. 主句為現(xiàn)在或?qū)頃r態(tài)主句謂語動詞如果是現(xiàn)在時或?qū)頃r，從句謂語動詞可用任何所需要的時態(tài)。e.g. She says that she works from Monday to Friday.I know he didn’t tell you that he would come then.He will tell me what happened to him during my absence.
2. 主句為過去時態(tài)主句的謂語動詞是一般過去時，從句的謂語動詞要用相應(yīng)的過去時態(tài)。e.g. He said there were no classes yesterday afternoon.He asked me if I was reading the book Red and Black when he came in.
3. 表示客觀事實或真理如果從句表示客觀事實或真理，不管主句的謂語動詞是何時態(tài)，從句都要用現(xiàn)在時態(tài)。e.g. The teacher said that the world is made up of matter.

（三） 表語從句:

1. 表語從句的基本用法:

1. 基本結(jié)構(gòu)：主語＋系動詞＋表語從句，常用的系動詞有be，seem，remain，look等。e.g. My idea is that you should make good use of your time.It seems that he has been to America.
2. as if/ as though引導(dǎo)的表語從句，系動詞通常為look，seem，sound等，從句可以用陳述語氣，也可以用虛擬語氣。e.g. It looks as if it is/ were going to snow.
3. that和what引導(dǎo)的表語從句的區(qū)別：that引導(dǎo)表語從句時，起連接作用，沒有實際意義，不作句子成分；what引導(dǎo)表語從句時，既充當(dāng)連接代詞，又作句子成分。e.g. Our plan is that we’ll go there once a week.That’s what he said.
4. 由連接副詞引導(dǎo)的表語從句：連接副詞where，why，when等引導(dǎo)表語從句，分別在從句中作地點、原因、時間狀語。e.g. That is where the great writer used to live.That is why he didn’t pass the exam.That was when I was thirty.2．表語從句需要注意的問題
5. 主語為名詞reason，表語從句用that而不用why引導(dǎo)。e.g. The reason why he was absent from the meeting was that he fell ill suddenly.The reason for such a serious accident is that the driver was too careless and drunk.
6. 引導(dǎo)表語從句時，用whether，不能用if。e.g. The question is whether he has signed the contract. (不能用if)
7. 表語從句中的虛擬語氣：如果主句的主語是名詞idea, advice, suggestion, order, request, requirement等時，則表語從句的謂語應(yīng)用虛擬語氣，“(should＋)動詞原形”。e.g. My suggestion is that we (should) set out at once.The doctor’s advice is that you (should)rest more and drink more.
8. 使用連接詞時的注意事項：連接代詞和連接副詞一般都表疑問，但what, when和where等連接詞有兩種含義，一種表示疑問，一種表示陳述。表陳述時，相當(dāng)于the thing that, the time when, the place where, 常意為“……的人/事”、“……的時間”、“……的地點”等。e.g. This is where he once lived.This is what I want to know.That was when he did the experiment.

1. 比較三個句式:

（四）同位語從句:在主從復(fù)合句中作同位語的從句，叫同位語從句。表示名詞的內(nèi)容，加以解釋。同位語從句的基本用法：

1. 能接同位語從句的名詞：fact, idea, news, promise, information, message, belief, doubt, hope, opinion, possibility, thought, wish, truth, question, problem, reply, answer, report, suggestion, advice, order, warning等等。
2. that引導(dǎo)的同位語從句：e.g. We were very excited at the news that our Chinese athletes won many gold medals.The problem that they can’t get here early is hard to solve.溫馨提示:同位語從句通常由that引導(dǎo)，但根據(jù)接同位語的名詞不同，也可由whether, when, who, how, what, why等引導(dǎo)。e.g. I have no idea when he will be back.The question who was to blame has never been settled.