主語從句如何使用(2)
主語從句如何使用
主語從句的作用
第一部分
常規主語從句，即句子在復合句中充當一個主語
主語從句的時態不受主句時態的影響和限制
(1)That he finished writing the composition in such a short time surprised us all.
(2)Whether we will go for an outing tomorrow remains unknown.
(3)Who will be our monitor hasn't been decided yet.
(4)Whom we must study for is a question of great importance.
(5)What caused the accident remains unknown.
(6)Whatever you did is right.
(7)Whom the watch belongs to is unknown.
(8)What we need is time.
(9)What we need are good doctors.
名詞性從句的時態規則：
1)、主句謂語動詞是現在或將來時，從句謂語動詞可以用任何需要的時態。
I wonder what he is doing now.
Do you know when and where he was born?
I'll write to tell him where I 'll meet him.
2)、主句謂語動詞是過去時，從句謂語動詞一般需用過去時。
(1)從句與主句的謂語動作同時發生，從句用一般過去時或過去進行時。
I thought that he studied hard.
He told me his son was watching TV.
(2)從句謂語動作在主句謂語動作之后，從句用過去將來時。
He said he would spend his holidays in Qingdao.
(3)從句謂語動作在主句謂語動作之前，從句用過去完成時。
They told me they had waited for me half an hour.
(4)從句如果有表示過去某一具體時間的狀語，仍用過去時。
She told me her brother died in 1945.
3)客觀的條件，從句時態不受絲毫影響。
(1)從句說明的是不受時間限制的事實或真理(客觀真理)。
The teacher told us that the earth turns from west to east.
He said Asia is the largest continent.
It was true that water freezes at thirty-two degrees Fahrenheit.
(2)當從句表示的是反復出現的時態不變。
She told me that she gets up at six o'clock every morning.
He asked me when the train usually starts.
(3)當從句是用來表達解釋科技內容時時態不變。
(4)當從句的謂語動作仍在繼續時，或者表示現在仍在的狀態時，時態不變。
He said that the workers in that factory are trying to fulfill the task in time.
She told me the other day that she is only 10.
(5)當從句的動作狀態還未發生，要用一般式表示。強調與現在的聯系。
He said he will wait for me this evening.
小結:
(1)引導主語從句連詞有that,whether,who,what,whatever等
(2)連詞位于句首不能省略
(3)主語從句大多數情況下視為第三人稱單數，但也有例外，如例(9)
注意：當what引導的名詞性分句作主語時，主謂一致問題極為復雜。著名學者周海中教授在論文《關于what-分句作主語的主謂一致問題》中就這一問題做了深入研究，并給出了10種的主謂一致關系。這些一致關系值得英語學習者和使用者特別注意。
第二部分
為了防止句子頭重腳輕，通常把形式主語it放在句首位置，真正主語擱置于句末
(1)It is certain that he will win the match.
(2)It is true that he has made a very important discovery in chemistry.
(3)It is very likely that they will hold a meeting.
(4)It is strange that he should do that.
(5)It is important that we all should attend the meeting.
(6)It is strange that the man should have stuck to his silly ideas.
(7)It is a pity that we won't be able to go to the south to spend our summer vacation.
(8)It is still a mystery what caused the accident.
(9)It is said that he has gone to shanghai.(=He is said to have gone to shanghai)
(10)It is known to all that the gun powder was first invented by the Chinese.
(11)It is suggested that the work should be done with great care.
(12)It happened that the two cheats were there. (=The two cheats happened to be there)
小結:
(1)為避免頭重腳輕，常以形式主語it引導從句。 It+形式主語謂語+從句。
(2)由于主語從句一般被認為是單數形式，形式主語的謂語動詞、be動詞+表語 均為單數第三人稱形式或過去式.
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