主語從句語法詳解
在英語中，主語從句是非常重要的一個語法知識，主語從句涉及的知識也非常多，需要我們耐心去理解，要不然容易混淆。下面是小編給大家帶來的英語語法主語從句_主語從句語法詳解，以供大家參考，我們一起來看看吧!
▼主語從句的概念與類型
主語從句在複合句中作主句的主語,引導主語從句的詞有從屬連詞that, whether以及連接代詞who, what,which, whoever, whatever, whichever和連接副詞when, where, why, how等.
例如:
That she was chosen made us very happy.
她當選了使我們很高興.
What caused the accident is a completemystery.
是什麼導致了這次事故還完全是一個謎.
Whether she will come or not is still a question.
她是否來還是一個問題.
Which team will win the match is stillunknown.
哪個隊會贏得這場比賽還不知道.
Whoever comes to the party will receive apresent.
參加聚會的每一個人都將收到一份禮物.
When they will start has not been decidedyet.
他們何時出發還沒決定.
注意:上述例句中的主語從句都是放在句首,但有時爲了使句子結構平衡,避免"頭重腳輕",常用it作形式主語,而把從句放在後面.
例如:
It is a pity that she has made such amistake.
她犯了這樣一個錯誤,真是遺憾.
It depends on the climate whether they aregoing shopping today.
他們是否今天去購物還得看天氣情況.
這樣就構成了下面一些常用句型:
1)It is + adj. / n. +從句
It is a pity/shame that...遺憾的是……
It is possible that...很可能……
It is unlikely that...不可能……
2)It +不及物動詞+從句
It seems/appears that...似乎……
It happened that...碰巧……
3)It + be +過去分詞+從句
It is said that...據說……
It is known to all that...衆所周知……
It is reported that...據報道……
It is believed that...據信……;人們相信……
It is suggested that...有人建議……
It must be pointed out that...必須指出……
It has been proved that...已證明…….
例如:
It is believed that at least a score ofbuildings were damaged or destroyed.
據信,至少有二十座樓房遭到破壞或徹底毀掉.
It is suggested that the meeting should beput off.
有人建議會議延期召開.
It's reported that three people were killedin the accident and five were hurt badly.
據報道,事故中三人喪生,五人重傷.
It is known to all that Taiwan is aninseparable part of China.
衆所周知,臺灣是中國不可分割的一部分.
▼主語從句的語法
<例句>
It's certain that prices will go up.
物價肯定要上漲的。
<語法分析>
主語從句可以由that引導，此外還可由連接代詞或連接副詞引導，關係代詞what或whatever也可引導主語從句。由that引導的主語從句是用的最多的一種主語從句，有時爲了強調，可以把從句放在句首，而絕大部分主語從句則藉助先行主語放到句子後部去。
<觸類旁通>
(1)That she hasn't phoned is odd.
她沒有來電話很奇怪。
語法分析：that引導的主語從句。
(2)That he was chosen made a tremendous stir in his village.
他被選中在他村子裏引起很大轟動。
語法分析：有時爲了強調或謂語較長時，可以把從句放在句首。
(3)It is natural that they should have different views.
他們有不同觀點是很自然的。
語法分析：it+be+形容詞或名詞+that從句。
(4)It happened that he wasn't in that day.
恰巧他那天不在。
語法分析：it+動詞+that從句。
(5)It's doubtful whether we'll be able to come.
我們是否能來還是個疑問。
語法分析：連接代詞或連接副詞可引導主語從句。
(6)What will be,will be.
該發生的事，總會發生。
語法分析：關係代詞型what也可引導主語從句。
<鞏固練習>
(1)______ he is still alive is a consolation.
(2)It's strange ______ she knows nothing about it.
(3)It may be ______ you'll prove yourself the most suitable.
(4)______ is to be sent there hasn't been decided.
(5)It was clear enough ______ she meant.
(6)______ is over is over.
(7)______ he says goes.
(8)______ she saw made her tremble.
<參考答案>
(1)That (2)that (3)that (4)What (5)what (6)What (7)Whatever (8)What
▼主語從句的注意問題
1)引導詞that與what
what既有引導主語從句的作用,同時又在從句中作句子成分(主語、賓語、表語等).這時what相當於all that/everything that...,常譯成"所……的(東西、事情、話等.)";而that只起連接作用,本身無實際意義,在從句中也不擔當任何句子成分.但that引導的主語從句放在句首時,不能省略that.
例如:
What is done can't be undone.
(諺語)已成定局,無可挽回.
What we can't get seems better than what wehave.
我們得不到的東西似乎比已得到的要好. That we should work out a plan to deal with the present serioussituation is important.
我們應該制定一項計劃來應付目前嚴峻的形勢,這一點非常重要.
That a new teacher will come to teach usgeography is true.
一位新老師將來教我們地理,這是真的.
▼主語從句的語氣
在It is necessary / natural/ important / strange...+ that-clause
這類句型裏,that所引導的主語從句中謂語動詞用"should+原形",表虛似語氣.
例如:
It is necessary that the problem should besettled at once.
這個問題必須馬上解決.
It's strange that he should have gone awaywithout telling us.
他竟然沒向我們說一聲就走了,真是奇怪.
鞏固練習
15. It isnecessary that a college student _______ at least a foreign language.
A. masters ld master C. mastered D. will master
四、以it作形式主語的主語從句與強調句型的區別
"It be + adj./n. + that-clause"與強調句型均有It ...之類的語言標誌,但不同的是:①前者中的that從句是主語從句.若刪掉其中的It be和that,則剩餘部分不論結構還是語意都不能成爲一個句子;但若將後者中的It be和that去掉,則剩餘部分的結構和語意仍能構成一個完整的句子.②強調句型譯爲漢語時可加上"正是……"或"就是……"之類的字眼,而主語從句則不可以.
請比較下面兩個句子:
It is surprising that Mary should have wonfirst place.
令人驚奇的是瑪莉竟然獲得了第一名. It is Mary that has won first place.
正是瑪莉得了第一名.
第一句話中的It是形式主語,that引導的是主語從句.句中的It is和that無法刪除,一旦刪除句子就不成立.
第二句是強調句型,其中的It is和that可以去掉,因爲沒有It is和that句子仍然很通順.
