主語從句
定義
在複合句中充當主語成分的句子叫做主語從句.
名詞性從句(主語從句、賓語從句、表語從句和同位語從句) 中的連接詞
連詞: that / whether / as if (though);
連接代詞: what / who/ which / whose / whatever / whoever / whomever / whichever，
連接副詞: where / when / why / how / wherever / whenever
第一部分
常規主語從句，即句子在複合句中充當一個主語
主語從句的時態：不受主句的時態影響和限制。
(1)That he finished writing the composition in such a short time surprised us all.
that在主語從句中有三個特點：不作成分;沒有詞義;不能省略。
(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. (主語從句大部分情況看成第三人稱單數形式)
(7)What we need is time.
(8)What we need are good doctors. (主語從句有時可以根據表語來判斷單複數問題)
小結:
(1)引導主語從句連詞有that, whether, who, what, whatever等
(2)連詞位於句首不能省略
(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(8)
第二部分
為了防止句子頭重腳輕，通常把形式主語it放在主語位置，真正主語擱置於句末
(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.
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(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.
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(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.
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(12)It seems that he has seen the film.(=He seems to have seen the film)
(13)It happened that the two cheats were there. (=The two cheats happened to be there)
小結:
(1)以that 引出的主語從句,常以形式主語it引導.
It is +形容詞/名詞/某些動詞ed/ + that 從句.
It +不及物動詞 + that 從句.
(2) 在有些that從句中要用虛擬語氣 (should+do/should+have done)例句4,5,6,11.
主語從句的用法。
主語從句與賓語從句兩者的用法和在句中的作用是不同的，下面從它們的各自用法來介紹。
一.主語從句
主語從句是在複合句中充當主語的從句，通常放在主句謂語動詞之前或由形式主語it代替，而本身放在句子末尾。
1. It 作形式主語和it引導強調句的比較
①主語從句常用it作形式主語，一般常用句型為：It is+{名詞/形容詞/過去分詞}+主語從句或It +不及物動詞 + that 從句. 例如：
It is still a question whether she will come or not.
It is strange that you should like him.
It is still unknown which team will win the match.
It seems that he has seen the film.
另外，還有一些比較多見的結構：
It turned out that……;
It has been proved that……;
It happened/occurred that……;
It is well-known that……等等
②而強調句則不同，它的結構是：It+be+被強調部分+that+從句
強調主語：It is the times that produce their heroes.時勢造英雄
強調賓語：It is English that Professor Lin teaches us.
強調狀語：It was in shanghai that I saw the film.
判斷是否是強調句有一個方法，就是將that以後的「句子的其餘部分」拿出來單獨看，看有沒有缺成分，缺的是什麼成分，再把謂語動詞後面that前面的那部分，帶到你認為缺成分的地方，如果放進去是一句完整的句子了，那就說明是強調句。
2. 用it 作形式主語的結構
(1) It is +名詞+that從句
It is a fact that … 事實是…
It is an honor that …非常榮幸
It is common knowledge that …是常識
(2) it is +形容詞+that從句
It is natural that… 很自然…
It is strange that… 奇怪的是…
(3) it +不及物動詞+that從句
It seems that… 似乎…
It happened that… 碰巧…
(4) it is+過去分詞+that從句
It is reported that… 據報導…
It has been proved that… 已證實…
3. 主語從句不可位於句首的五種情況
(1) if 引導的主語從句不可居於複合句句首。
It is uncertain if he will leave for Beijing tomorrow.
if可以引導主語從句，但必須放置句尾。
(2) It is said , (reported) …結構中的主語從句不可提前。例如：
It is said that President Jingo will visit our school next week.
(3) It happens…, It occurs… 結構中的主語從句不可提前。例如：
It occurred to him that he failed in the examination.
(4) It doesn’t matter how/whether …結構中的主語從句不可提前。例如：
It doesn’t matter whether he is wrong or not.
(5) 含主語從句的複合句是疑問句時，主語從句不可提前。例如：
Is it likely that it will rain in the evening?
4. what 與that 在引導主語從句時的區別
what 引導主語從句時在從句中充當句子成分，如主語.賓語.表語，而that 則不然。例如： What you said yesterday is right.
主語從句翻譯題目
1. (誰將去接他)_____________ is not decided.
2. (哪個班極會贏得這場足球賽)________ is not clear so far.
3. (他能否買到飛機票)________________ doesn’t matter much.
4. (我們如何去那裡)_________________ is a question.
5. (你剛才告訴我的)________________ was really a surprise.
6. (他什麼時候出國)_________________ is being discussed
7. (他為什麼哭)_________________ is not clear.
8. It is clear__________(他是一個乞丐).
9. (你要請誰)_____________ is not important.
10. (我們將在哪裡舉行籃球賽)__________________ is not clear.
最佳答案
1. who will pick him up is not decided.
2. which class will win the match is not clear so far.
3. whether he can buy the ticket for plane doesn’t matter much.
4. how we will go there is a question.
5. what you told me just now was really a surprise.
6. when he will go abroad is being discussed
7. why he cries is not clear.
8. It is clear that he is a beggar
9. who you will invite is not important.
10. where the basketball will be held is not clear.