孫玉忠

主語從句是中學階段的重點語法項目，也是高考的熱點之一。主語從句在復合句中作主句的主語。其關系代詞和關系副詞有：that， whether， who， which， when， where， how， why等。

一、連接詞的選擇

按連接詞的用法特點，我們可以把主語從句分為三類：

1. 以that引導的主語從句，盡管that沒有實際意義，但也不能省略。如：

That she was wrong is obvious. 她錯了，這是很明顯的。

That we shall be late is certain. 我們將要遲到，這是顯而易見的。

【注意】 有時可用形式主語 it 代替主語從句，即將it 放在句首，把主語從句放在句末，以避免句子頭重腳輕。如：

It is doubtful whether he is coming. 他是否要來，是令人懷疑的。

It is hoped that the blacks will have equal rights. 我們都希望黑人能享有平等的權利。

2. whether 引導主語從句 ，不充當從句的任何成分。以whether（是否）引導的主語從句，不能用if來代替。如：

Whether they'll set out at 7：00 tomorrow morning is unknown. 明天他們是否要在7點出發(fā)，這是不知道的。

Whether she is coming or not doesn't matter too much. 她來不來都無關緊要。

【注意】 引導主語從句時只有用it作形式主語時，whether和if都能引導主語從句。如：

It hasn't been decided whether / if we shall attend the meeting. 我們是否去參加會議還沒有決定下來。

3. who， which， what， why， when， how等引導主語從句

這類連接詞也具有雙重作用，翻譯時這些連接詞與其作疑問詞的意思相當。有時也可用作形式主語it。如：

Which football team will win the match is unknown. 哪一個足球隊會贏得比賽，還不清楚。

What we need now is more rest. 我們現在所需要的是更多的休息。

How the prisoner escaped is a completely wrong. 囚犯如何逃走的是一個絕對的錯誤。

【注意】

1. 如果帶主語從句的句子是疑問句或感嘆句時，則必須用形式主語it。如：

Is it true that the scientist will give us a talk next week？ 那位科學家下星期要給我們作報告是真的嗎？

Has it been announced that when the planes are to take off？ 已經宣布飛機何時要起飛了嗎？

How strange it is that the children are so quiet！ 真奇怪，這些孩子那么地安靜！

2. what， whatever， whoever 等引導的主語從句，一般不用 it 作形式主語。如：

What he wants is a book. 他所想要的就是一本書。

Whoever leaves the room last should close the door. 無論是誰最后一個離開房間都要鎖好門。

二、謂語動詞的數

主語從句作主語，謂語動詞一般用單數;但 what 引導的從句作主語，代表復數概念（?？蓮谋碚Z上看出）時，謂語動詞則常用復數形式。如：

What we need is water. 我們所需要的是水。

What the boy wants are those red apples. 那個男孩想要的是那些紅蘋果。

三、主語從句中的語氣

在下列情形中，主語從句的謂語動詞用“should + 動詞原形”。

1. It is suggested / requested / proposed / desired / required ?that... ，主語從句中的謂語動詞也要用虛擬語氣。如：

It has been decided that the meeting （should） be put off. 已經決定推遲這個會議。

It is suggested that we （should） take the bus. 有人建議我們乘公共汽車。

2. 在用it作形式主語的時候，如果作表語的形容詞為necessary， important， impossible， strange， natural， advisable， desirable， urgent， essential等時，即“It + be + 形容詞 + 主語從句”，主語從句中的謂語動詞要用虛擬語氣，也就是“should+do”，should可以省略。如：

It is necessary that the problem （should） be discussed at once. 立刻討論這個問題很有必要。

It is strange that he （should） have so many friends. 太奇怪了，他有那么多的朋友。

四、whoever， whatever， whichever引導主語從句

whoever， whatever， whichever可引導主語從句。Whoever = anyone who; whatever = anything what; whichever = anything which。whatever和 whichever還可用作連接形容詞。如：

Whoever breaks the law should be punished. 無論是誰觸犯了法律，都應受到懲罰。

Whatever was said here should be kept a secret. 這里說的話都應當保密。

Whichever book she bought would be paid for. 無論她買了哪一本書都要付款。

五、強調句中的主語從句

為了達到某種表達效果，主語從句有時可用在強調句中。如：

It was what she said that made all the people present laugh. 就是她說的內容讓在場的人都大笑起來。

【考點精練】

I. 單句語法填空。

1. It suddenly occurred to him ___ he had left his keys in the office.

2. The limits of a person's intelligence， generally speaking， are fixed at birth， but ___ he reaches these limits will depend on his environment.

3. It doesn't matter ___ you turn right or left at the crossing—both roads lead to the park.

4. It is by no means clear ___ the president can do to end the strike.

5. Most of what has been said about the Smiths ___ （be） also true of the Johnsons.

6. It is required in the regulations that you

___ （tell） other people the password of your e-mail account.

7. As many five courses are provided， and you are free to choose ___ suits you best.

II. 從方框中選擇合適的詞填空（方框中的單詞數量可能多， 有的詞也許不是用一次）。

what， who， that， whether， because， if， where， when， why， how， whomever， whatever， whichever， ?whoever

1. ___ you don't like him is none of my business.

2. After Yang Liwei succeeded in circling the earth， ___ our astronauts desire to do is walk in space.

3. ___ leaves the room last ought to turn off the lights.

4. ___ he can finish his task on time is of great importance.

5. ___ they will solve the serious problem has not been decided.

6. ___ he did that wasn't quite clear.

7. ___ he said at the meeting astonished everybody present.

8. It is a fact ___ the English is being accepted as international language.

9. ___ the old man comes from is still a puzzle.

10. It won't make too much difference___ he will join us.