條件句 (Conditional Sentences)

條件句(If-條件句)是一種假設語氣。這些句子可分為兩半:一半是由帶有"If"的從屬子句,與另一半含有情態助動詞 (will, would, can, could, may, might)的主要子句所形成的複句

條件句的從屬子句是用來陳述條件,通常以"If"起頭,所以又稱為『If-子句』。條件句的主要子句則是用來說明結果。條件句主要有三大類,我們通常可以從If-子句主要子句中的動詞時態來判斷該條件句是屬於哪一類,進而了解句子的意涵。

下面這三個句子說明條件句因為所使用的時態不同,句子的語意也完全不一樣。

If I have enough money, I will marry you.

如果我有足夠的錢,我會和你結婚。

第一類條件句(相當有可能實現)
用現在簡單式表示將來有可能實現的假設。

If I had enough money, I would marry you.

如果我有足夠的錢,我會和你結婚。

第二類條件句(不太有可能實現)
用過去簡單式表示與現在事實相反的假設,現在的事實是我沒有足夠的錢,所以我不太有可能和你結婚。

If I had had enough money, I would have married you.

如果當時我有足夠的錢,我是會和你結婚。

第三類條件句(完全不可能實現)
用過去完成式表示與過去事實相反的假設,代表我當時沒有足夠的錢,否則我早就和你結婚了。雖然沒有指出時間點,但從時態就可以知道它所表達的是已經過去的「當時」。

第一類條件句

If + 現在簡單式 , ... + will
can
may
might
+ 動詞原式

第一類條件句的動詞時態在If-子句裡通常為現在簡單式,在主要子句裡為"(will, can, may, might)+動詞原式"。

使用第一類條件句,表示說話者認為if-子句中所陳述的假設,將來有可能實現。

If it rains, I will stay home.

如果下雨,我就呆在家裡。

從屬子句"If it rains"用來陳述條件:如果下雨……
主要子句"I will stay home" 說明結果:在"如果下雨……"的條件下,會有什麼樣的結果:"我就呆在家裡"。

If it rains, I won't go to the park.

如果下雨,我就不去公園。

主要子句也可以用否定形態: won't = will not
從屬子句"If it rains" 為現在式,主要子句"I won't go to the park"為未來式。

If you study hard, you will pass the exam.

如果你努力學習,你將通過考試。

假設你現在努力學習,未來就有可能『通過考試』。If從屬子句動詞為現在簡單式 study, 主要子句的動詞時態是情態助動詞 will + 動詞原式 pass。

If you don't hurry, you will miss the train.

如果你不趕快點,你會趕不上火車。

If you don't hurry, you might miss the flight.
= If you don't hurry, you may miss the flight.

如果你不趕快點,你可能會錯過航班。
may 當『可能』解釋時是可以和 might 互相取代的;這裡的情態助動詞 might 並不代表過去式。
may 若有『允許』的意思時是不可以被 might 取代,如: No one may enter without a ticket.

If you work hard and take responsibility, you can get ahead.

如果你努力工作,勇於承擔責任,你可以出人頭地。

摘錄自美國總統歐巴馬, 2014 國情咨文。

be going to 取代 will

If I lie to her, she will slaughter me.
= If I lie to her, she is going to slaughter me.

如果我騙她,她會宰了我。

第一類條件句的主要子句的動詞 will 有時會被 be going to 所取代。


第一類條件句除了上述表示未來的可能性,也可以用在:

第一類條件句用於迷信行為

If you whistle at midnight, the ghost will come to you.

如果您在午夜吹口哨,鬼會來找你。

If you break a bowl on New Year's Day, you will have bad luck for the whole year!

如果你在新年那一天打破了碗,你將有整整一年的霉運!

第一類條件句用於警告、恐嚇

If you don’t come to my wedding party, I will never see you again.

如果你不來參加我的婚禮派對,我再也不見你了。

If you say that one more time, I will smack you.

如果你再說一次,我會賞你一巴掌。

請將正確答案拖放到適當的空格內,再按Solve鈕看結果。

第一類條件句練習

  1. If we take the MRT, we   in time.
  2. If it  , the children won't go for a walk.
  3. They will go to the party if they   invited.
  4. If she doesn't read the novel, she   the literature test.
are arrive pass rained rains were will arrive won't pass

  • 如果我不與我的父親爭論,他會借給我他的車子。
  • If I did not argue with my father, he will lend me his car.
  • If I do not argue with my father, he will lend me his car.

第一類條件句: if + 現在簡單式, 主要子句: will + 動詞原式。

If we _______ now, we will catch the train.

(A) are leaving (B) have left (C) left (D) leave

第一類條件句的從屬子句有時也用現在進行式現在完成式

If you are doing homework now, I will come back later.

如果你正在做功課,我晚會兒再過來。

If it has stopped raining, we can go shopping now.

如果已經停止下雨,我們現在可以出去購物。

第一類條件句帶有表時間的從屬連接詞

條件句是由從屬子句與主要子句所組成的的一種複句,一般使用 If 從屬連接詞來連接前後兩個子句。又因為條件句是指在什麼條件下,會有什麼結果。這種從『條件』到『結果』是有時間因素存在的。因此許多表時間的從屬連接詞,例如: before, after, when, as soon as, until 等等,可以用來取代"If"的位置。

第一類條件句的從屬子句帶有表時間的從屬連接詞;主要子句的動詞是 will/be going to + 動詞原式,通常敘述未來將發生的事件。(通常主要子句放在從屬子句之前)

主詞 will
be going to
動詞原式 ... before
after
when
as soon as
until
主詞 現在簡單式

I'll finish this report before I go home.

回家之前我將會完成這份報告。

I'll marry you after I find a job.

在我找到工作後我會和你結婚。

He's going to study abroad when he graduates from high school.

當他高中畢業後他將出國留學。

We'll wait here until the bus comes.

我們將在這裡等到巴士來。

Please call me as soon as you get there.

一旦你到達那裡,請給我打個電話。


第二類條件句

If + 過去簡單式 , ... + would
could
might
+ 動詞原式

第二類條件句的動詞時態在If-子句裡通常為過去簡單式,主要子句為"(would, could, might)+動詞原式"。

使用第二類條件句,表示說話者認為if-子句所陳述的假設不太可能發生。通常它用於想像的、非真的、不可能的、或與現在事實相反的未來事件。

If I won the lottery, I would buy a house.

如果我中了樂透,我會買一棟房子。

想像中了樂透的未來事件。

If I were you, then I wouldn't do that.

如果我是你的話,我不會那樣做。

我不是你,所以我們用假設語氣來表示所說的與事實相反的假設。
當句子起頭是"If I were you"多半是給予忠告。第二類條件句的從屬子句(條件)若是Be動詞,不論那種人稱,都使用 were,不能用 was。

If you were nicer to her, she might lend you the bike.

如果你對她好些,她可能會借給你腳踏車。

事實上你對她不好,她不太可能會借你腳踏車。

  • 如果我會說日語,我會去日本工作。
  • If I speak Japanese, I would work in Japan.
  • If I spoke Japanese, I would work in Japan.

不太可能發生的假設,屬於第二類條件句: if + 過去簡單式, 主要子句: would + 動詞原式。

  • 如果你有更多的經驗,你可能會更容易找到一份工作。
  • If you are more experienced, you might have an easier time finding a job.
  • If you were more experienced, you might have an easier time finding a job.

事實上你的經驗還不夠多,與事實相反的假設,必須用 were。

第二類條件句的If-子句用過去進行式

If I were working now, I would have money to pay the rent.

如果我現在有在工作,我就有錢付房租。

使用過去進行式來表示與現在事實不相符的假設:如果我現在有在工作,事實上我現在沒有在工作。

If it weren't raining now, we could go shopping.

如果現在沒有在下雨的話,我們就可以去購物了。

使用過去進行式來表示與現在事實不相符的假設:如果現在不下雨,事實上現在還在下雨。

第二類條件句的If-子句帶有 could

If I could be a dragon for a day, I would probably use my fire to barbeque.

假如有一天我能成為一條龍,我可能會用我的火來燒烤。

If I could make that happen, it would be great!

如果我真能實現它的話,那就太棒了!


could = were able to 表示有能力。

第二類條件句與第一類條件句的比較

比較第二類條件句與第一類條件句
第一類條件句 If I have enough money, I will buy some new books.
如果我有足夠的錢,我會買一些新書。將來有可能發生
第二類條件句 If I had enough money, I would buy a mansion.
如果我真有足夠的錢,我會買了豪宅。 將來不太可能發生

第一類條件句表示將來有可能發生。而第二類條件句說明將來不太可能發生的事。請注意兩者時態的用法。


第三類條件句

If + 過去完成式 , ... + would
could
might
+ have + 過去分詞

第三類條件句的動詞時態在If-子句裡為過去完成式,主要子句為"(would, could, might)+have+過去分詞"。

使用第三類條件句,通常表示if-子句中所論及的過去事件沒有發生,因而造成主要子句所說的無法實現。有些後悔過去要是如何的話(事實上並沒有發生),今天會有不同的結局。

If I had studied hard, I would have passed the exams.

如果我在過去有努力學習,我就會已經通過考試了。

後悔過去沒努力學習 ,以致於考試沒有通過。

If David had been taller, he could have played in the NBA.

如果大衛有再高一點的話,他就可以在NBA打球了。

If I hadn't spent money on lotteries, I could have bought a house by now.

如果我沒花錢在樂透上的話,我現在就已經買了房子了。

後悔過去把錢都花在買樂透,要不然我現在就可以買一棟房子。

  • 如果你沒有看到它,你可能不會相信。
  • If you haven't see it, you probably wouldn't have believed it.
  • If you hadn't seen it, you probably wouldn't have believed it.

第三類條件句的主要子句的情態助動詞也可以用否定形態: wouldn't = would not。

If we had started earlier, we _______ the deadline.

(A) will have met (B) will meet (C) would meet (D) would have met

If I _______ my own business right after graduation, I would have been a millionaire by now.

(A) had started (B) started (C) start

  • 如果我知道你在醫院,我會去探望你。
  • If I knew you were in the hospital, I would have visited you.
  • If I had known you were in the hospital, I would have visited you.

第三類條件句:If ...過去完成式, 主要子句: would have + p.p.

  • 如果警察不在那裡,他可能已經跑掉了。
  • If the policeman hasn't been there, he might have gotten away with it.
  • If the policeman hadn’t been there, he might have gotten away with it.

第三類條件句:If ...過去完成式, 主要子句: might have + p.p.

第三類條件句的If-子句用過去完成進行式

If he had been paying attention to Google's share price, he would have made a fortune by now.

如果他有在關注著谷歌的股價,他現在就已經發財了。

If she had been wearing her seatbelt, she _______ the car accident.

(A) might have survived (B) can survive (C) may survive (D) will survive


If-子句與主要子句出現的順序並不重要

注意:上面所述三類條件句的例子的if-子句都在句前,接著逗號 「,」,然後主要子句。我們可以把主要子句移至前面,if-子句放在後面,並省掉逗號「,」。

If you study hard, you will pass the exam.
= You will pass the exam if you study hard.

If I won the lottery, I would buy a house.
= I would buy a house if I won the lottery.

If I had studied hard, I would have passed the exams.
= I would have passed the exams if I had studied hard.



除了上述三種基本句型都是帶有條件的假設語氣,另有一種非條件的假設語氣,主、從句皆為現在式,且主要子句不需要有情態助動詞。這一類的條件句屬於無(零)條件的假設語氣,故稱之為第零類條件句。

第零類條件句

If
When
Unless
+ 現在簡單式 , + 現在簡單式

第零類條件句主要子句與從屬子句所使用的動詞時態通常都是現在簡單式

第零類條件句用來陳述一般事實、習慣行為、不變定律、或科學真理,它是指『只要條件吻合,結果一定發生』。通常以 "If", "When", 或 "Unless" 當作句子的起頭。If 與 When 通常可以互用,不會改變句子的語意。

If you heat ice, it melts.
= When you heat ice, it melts.

假如你把冰塊加熱,它會融化。

If you heat water to 100 degrees, it boils.
= When you heat water to 100 degrees, it boils.

如果你把水加熱到攝氏100度,它會沸騰。


  • 如果沒有空氣,木材不會燃燒。
  • If there was no air, wood doesn't burn.
  • If there is no air, wood doesn't burn.

一般事實或科學真理,主、從句皆為現在式。

  • 如果鐵受潮濕,它會生鏽。
  • If iron got wet, it rusts.
  • If iron gets wet, it rusts.

一般事實或科學真理,主、從句皆為現在式。

When I finish an article, I always ask Jane to read it through.

當我完成了一篇文章,我總是請珍讀一遍。

表示習慣性的行為。

If Judy has homework to do, she does it right away.

如果茱蒂有功課要做,她馬上就去做。

表示習慣性的行為。

Unless he asks you politely, refuse to do any more work for him.
= If he doesn't ask you politely, refuse to do any more work for him.

除非他有禮貌地問你,否則拒絕為他做更多的工作。

Unless = Not if

  • 如果她心情不好,她就去血拼(購物)。
  • When she was sad, she goes shopping.
  • When she is sad, she goes shopping.

第零類條件句,表示習慣性的行為。

  • 除非Cindy戴眼鏡,否則她是無法開車的。
  • Unless Cindy has worn glasses, she can't drive.
  • Unless Cindy wears glasses, she can't drive.

第零類條件句,陳述一般事實。unless = if not

第零類條件句的If-子句用現在進行式

If I am driving, I never answer my cellular phone.

如果我開車,我從來不接手機。

在開車的時候(進行式),我有不接手機的習慣。

Grammar



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