子句與複合句中級

條件句

Q: 英文的條件句有幾種？

有四種基本類型加上一種混合型。第 0 類談事實、永遠成立的流程；第 1 類談可能發生的事；第 2 類是與現在事實相反的假設；第 3 類是與過去事實相反的假設；混合條件句則在條件與結果分屬不同時間時，把第 2 類和第 3 類混合使用。在多益中，第 1 類、第 3 類以及 Should/Had 倒裝出現得最多。

Q: 為什麼第一類條件句的 if 子句不用 will？

英文中表示條件和時間的子句（if, unless, when, as soon as, in case...）用現在式來表達未來；will 只放在主要子句。所以要寫 If the client agrees, we will sign，而不是 If the client will agree。Part 5 很常把 will 放進 if 子句的選項當陷阱。

Q: 第二類條件句要用 "were" 還是 "was"？

正式書面語不論主詞都用 were：If I were you、If the price were lower。日常口語中可能會聽到 "If I was..."，但在考試和商務文件中，請選 were。倒裝形式也只用 were：Were I the manager, ...。

Q: 混合條件句什麼時候用？

用於條件與結果不在同一時間的情況。最常見的是過去的條件，現在的結果：If I had accepted the offer, I would be living in London now（if 子句是第 3 類，主要子句是第 2 類）。辨識線索是 if 子句有 had + V3，而主要子句有 now, today, currently 等表示現在的字詞。

Q: "Unless" 和 "if not" 完全一樣嗎？

大部分情況下 unless = if ... not：Unless you register, you cannot attend = If you do not register, ...。unless 之後用肯定動詞，不再加 not。不過 unless 的意思是「除非」，所以較少用於與過去事實相反的假設或表達情緒：I will be surprised if he doesn't come 就不能改成 unless。

Q: "Should you have any questions" 是什麼意思？

這是第一類條件句的倒裝，等於 If you have any questions（如果您有任何疑問）。結構是 Should + S + 原形動詞，後半句通常是客氣的祈使句，例如 please contact。這個句型在多益的書信和公告中不斷出現，所以看到句首空格、後面接 you + 原形動詞 時，答案幾乎一定是 Should。

Conditionals

第 0、1、2、3 類與混合條件句；unless、provided that、as long as、in case、otherwise 等 if 的替代用語；以及 Should/Were/Had 倒裝。

編寫：OpenTOEIC更新日期: 2026年10月18日

練習 60 題

四種基本條件句

if 子句可以放在主要子句前面（加逗號），也可以放在後面（通常不需要逗號）。

類型	if 子句	主要子句	使用時機
0	現在簡單式	現在簡單式	事實、永遠成立的流程
1	現在簡單式	will/can/may + V，或祈使句	現在或未來可能發生的事
2	過去簡單式（be → were）	would/could/might + V	與現在事實相反或不太可能發生的假設
3	過去完成式	would/could/might + have + V3	與過去事實相反的假設、遺憾

例句

If the printer runs out of toner, a warning light comes on.如果印表機的碳粉用完，警示燈就會亮起。
If you place your order by noon, it will ship the same day.如果你在中午前下單，商品會在當天出貨。
If we had a larger budget, we would hire two more designers.如果我們有更多預算，就會再聘請兩位設計師。
If the team had checked the figures, the error would not have occurred.如果團隊當時檢查過數據，就不會發生那個錯誤。

第一類條件句：常見的變化形式

第一類條件句談的是現在或未來可能發生的事。除了基本句型 If + 現在簡單式, will + V 之外，商務文件還常用許多變化形式。共同點是：if 子句仍用現在式，主要子句則可以變化。

主要子句是祈使句或請求，在書信和公告中非常常見：If you have any questions, please contact us.
主要子句用 can, may, must, should 取代 will：If the item is damaged, you may return it within 30 days.
if 子句用現在進行式或現在完成式：If you are traveling next week, ...、If you have finished the test, you may leave.
If + S + should + V 表示不太可能發生的事，語氣更客氣：If you should need help, call me. 省略 if、把 should 移到句首就成為 Should you need help, ...（見倒裝一節）。
will 只有在表示願意或客氣的邀請時才會出現在 if 子句：If you will follow me, I will show you to your seat. 這不是表示未來的 will，多益幾乎不會要求選這種形式。

例句

If the shipment arrives late, we will notify you by e-mail.如果貨物延遲送達，我們會以電子郵件通知您。
If you haven't received your badge, please visit the security office.如果您還沒拿到識別證，請到警衛室領取。

第二類條件句：were、were to 與 could、might

第二類條件句談的是與現在事實相反或不太可能發生的事。if 子句退回過去簡單式，但意思仍指現在或未來。

遇到 be 動詞時，正式文體不論主詞都用 were：If the office were closer, I would walk to work. 口語中仍有人用 was，但多益的答案一律是 were。
If I were you, I would... 是提出建議的慣用說法。
If + S + were to + V 表示說話者認為不太可能發生的未來假設：If the company were to relocate, many employees would resign.
主要子句用 could（就能夠）或 might（或許會）取代 would 來改變語氣：If we had more staff, we could open on Sundays.
與第一類的區別：同樣的意思，第一類是實際可能（If we get the contract, we will hire more staff），第二類是假設、不太可能（If we got the contract, we would hire more staff）。

例句

If I were in charge of the project, I would extend the deadline.如果由我負責這個專案，我會延後截止日期。
If the store stayed open later, it might attract more customers.如果這家店營業到更晚，或許能吸引更多顧客。

混合條件句

當條件與結果分屬不同時間時，可以把第二類和第三類混合使用。

If + 過去完成式, S + would + V (過去 → 現在的結果)If + 過去簡單式, S + would have + V3 (現在的狀態 → 過去的結果)

例句

If I had accepted the job in London, I would be living there now.如果我當初接受了倫敦的那份工作，現在就會住在那裡。
If she were more organized, she would have finished the report on time.如果她更有條理（實際上並非如此），就會準時完成報告。

Unless、provided that、as long as、in case、otherwise

unless = if ... not：Unless we receive payment by Friday, the order will be cancelled. unless 之後用肯定動詞。
provided (that) / providing (that) / as long as / on condition that = 只要、唯有在…條件下：You may work from home provided that you attend Monday meetings.
in case = 以防萬一（事先做某事以防不測），和 if 不同：Bring an umbrella in case it rains（無論如何都帶著傘），而 Take a taxi if it rains（只有下雨時才搭計程車）。in case 之後不用 will。
otherwise = 否則；是副詞，連接兩個句子：Please confirm by Tuesday; otherwise, your seat will be released.
even if = 即使；only if = 只有在…時（放在句首時主要子句要倒裝：Only if all parties agree can the contract be signed.）。
but for / without + N = 若非、要不是：But for your help, we would have missed the deadline.

例句

The discount applies as long as the invoice is paid within 10 days.只要發票在 10 天內付清，折扣就適用。
I'll send you a copy of the agenda in case you can't find yours.我會寄一份議程給你，以防你找不到自己的那份。

省略形式的 if 片語：if necessary、if possible、if so、if any

多益的書信和公告大量使用省略了主詞和動詞的 if 片語。它們常出現在 Part 6 和 Part 7，有時也會在 Part 5 以選字完成片語的形式出現。

if any 搭配名詞，意思是「即使有也很少」：There are few, if any, seats left. 別和 if so 混淆，if so 代替的是前面整個子句。

片語	意思	例句
if necessary / if needed	如有必要	We can extend the deadline if necessary.
if possible	如果可能的話	Please reply by Friday, if possible.
if so	如果是這樣（回應前一句）	Are you free on Monday? If so, let's meet at 10.
if not	如果不是／否則	Is the room available? If not, please book another one.
if any	如果有的話（通常放在兩個逗號之間）	Corrections, if any, should be sent by noon.
unless otherwise stated / noted	除非另有說明	Unless otherwise stated, all prices include tax.

條件句的倒裝

正式文體（書信、公告）省略 if，把助動詞移到句首。這是 Part 5 非常常見的題型。

否定時把 not 放在主詞之後，不用縮寫：Had we not received the email...（不寫 *Hadn't we received*）。

類型	一般寫法	倒裝
1	If you (should) need help, call us.	Should you need help, call us.
2	If I were the manager, I would...	Were I the manager, I would...
2 (to V)	If we were to cancel, ...	Were we to cancel, ...
3	If we had known, we would have...	Had we known, we would have...
若非	If it were not for the subsidy, ...	Were it not for the subsidy, ...
若非（過去）	If it had not been for his help, ...	Had it not been for his help, ...

例句

Should you have any questions about your bill, please contact our support team.若您對帳單有任何疑問，請聯絡我們的客服團隊。
Had the shipment been insured, the company would have recovered its losses.如果當時貨物有投保，公司就能彌補損失了。

多益解題技巧

Part 5 常給出完整的一個子句，要求選出另一子句的時態。看已有的動詞：will/can + V → if 子句用現在簡單式；would + V → 過去簡單式；would have + V3 → 過去完成式。第一類條件句的 if 子句不用 will。
句子以空格開頭，接著是 you + 原形動詞 ... , please contact... → 答案是 Should（if you should 的倒裝）。這是多益書信、公告中極為常見的句型。
句首空格後接 S + V3/ed，而後半句有 would have → Had。後面接 it not for + N → Were。
選連接詞：unless = if...not；provided/providing (that)、as long as = 只要、在…條件下；in case = 以防萬一（不是「如果」）；otherwise 是副詞 = 否則，通常接在句號或分號之後。

常見錯誤

錯誤: If the client will agree, we will sign the contract tomorrow.

正確: If the client agrees, we will sign the contract tomorrow.

第一類條件句的 if 子句用現在簡單式，不用 will。

錯誤: If I would have known about the delay, I would have rebooked.

正確: If I had known about the delay, I would have rebooked.

第三類條件句的 if 子句用過去完成式，不用 would have。

錯誤: Unless you do not register, you cannot attend.

正確: Unless you register, you cannot attend.

unless 本身已含否定意義，不再加 not。

錯誤: Should you needed assistance, please ask the front desk.

正確: Should you need assistance, please ask the front desk.

Should + S 之後用原形動詞。

練習題（附解答）

1.If the client ------- the contract by Friday, we will begin production next week.
1. (A) will sign
2. (B) signed
3. (C) would sign
4. (D) signs
查看解答與解析
答案: (D) signs
主要子句 will begin → 第一類條件句，if 子句用現在簡單式：signs。第一類條件句的 if 子句不用 will；signed/would sign 屬於第二類。
2.If the company ------- a larger office, it would hire ten more engineers this year.
1. (A) had
2. (B) has
3. (C) will have
4. (D) has had
查看解答與解析
答案: (A) had
主要子句 would hire → 第二類條件句（與現在事實相反的假設），if 子句用過去簡單式：had。has/will have 屬於第一類；has had 不用於第二類的 if 子句。
3.If we had ordered the materials earlier, the project ------- on schedule last month.
1. (A) will finish
2. (B) finishes
3. (C) would have finished
4. (D) would finish
查看解答與解析
答案: (C) would have finished
if 子句是過去完成式 had ordered，主要子句有過去的時間標記 last month → 第三類條件句：would have finished。would finish 談論現在／未來，與 last month 不符；will finish、finishes 屬於第一類／第零類，不能搭配過去完成式的 if 子句。
4.If Mr. Tanaka had accepted the transfer to Osaka, he ------- there now.
1. (A) will live
2. (B) lives
3. (C) had lived
4. (D) would be living
查看解答與解析
答案: (D) would be living
混合條件句：條件在過去（had accepted），結果在現在（now）→ would + V: would be living。其餘選項都不是假設語氣主要子句的形式。
5.------- you have any questions about your reservation, please contact the front desk.
1. (A) Had
2. (B) Should
3. (C) Were
4. (D) Unless
查看解答與解析
答案: (B) Should
___ you + 原形動詞 ..., please contact 句型 → 第一類條件句倒裝：Should you have = If you have。Had 需接 V3，Were 需接 to V/N；Unless 語意相反。
6.------- the shipment been insured, the firm would have recovered its losses.
1. (A) Should
2. (B) If
3. (C) Had
4. (D) Were
查看解答與解析
答案: (C) Had
句首空格 + S + been (V3)，後面子句是 would have recovered → 第三類條件句倒裝：Had the shipment been = If the shipment had been。If 缺少 had；Should/Were 在此不能搭配 V3。
7.------- it not for the generous sponsorship, the festival could not take place this year.
1. (A) Had
2. (B) Should
3. (C) If
4. (D) Were
查看解答與解析
答案: (D) Were
___ it not for + N 句型，主要子句 could not take place（現在）→ Were it not for = If it were not for。Had it not been for 用於過去；If 缺少動詞。
8.Your registration will be cancelled ------- you pay the fee by May 10.
1. (A) if
2. (B) provided that
3. (C) unless
4. (D) as long as
查看解答與解析
答案: (C) unless
語意：如果不繳費，報名就會被取消 → unless = if ... not。if、provided that、as long as 都是肯定語意，會讓句子變成「如果你繳費就會被取消」。
9.The technician recommends keeping a spare battery ------- the main one fails during the presentation.
1. (A) unless
2. (B) in case
3. (C) otherwise
4. (D) so that
查看解答與解析
答案: (B) in case
in case = 以防萬一：事先準備，以防主電池故障。unless 語意錯誤；otherwise 是副詞；so that 表示目的（沒有人希望電池故障）。
10.Please submit your expense report by Thursday; -------, reimbursement will be delayed until next month.
1. (A) otherwise
2. (B) unless
3. (C) in case
4. (D) provided
查看解答與解析
答案: (A) otherwise
位於分號之後、逗號 + 子句之前 → 需要副詞 otherwise（否則）。unless、in case、provided 是連接詞，後面必須直接接子句。

練習題

60 題 Part 5 題型，一次一題，每題作答後立即附上解析。

開始練習

常見問題

英文的條件句有幾種？

有四種基本類型加上一種混合型。第 0 類談事實、永遠成立的流程；第 1 類談可能發生的事；第 2 類是與現在事實相反的假設；第 3 類是與過去事實相反的假設；混合條件句則在條件與結果分屬不同時間時，把第 2 類和第 3 類混合使用。在多益中，第 1 類、第 3 類以及 Should/Had 倒裝出現得最多。

為什麼第一類條件句的 if 子句不用 will？

英文中表示條件和時間的子句（if, unless, when, as soon as, in case...）用現在式來表達未來；will 只放在主要子句。所以要寫 If the client agrees, we will sign，而不是 If the client will agree。Part 5 很常把 will 放進 if 子句的選項當陷阱。

第二類條件句要用 "were" 還是 "was"？

正式書面語不論主詞都用 were：If I were you、If the price were lower。日常口語中可能會聽到 "If I was..."，但在考試和商務文件中，請選 were。倒裝形式也只用 were：Were I the manager, ...。

混合條件句什麼時候用？

用於條件與結果不在同一時間的情況。最常見的是過去的條件，現在的結果：If I had accepted the offer, I would be living in London now（if 子句是第 3 類，主要子句是第 2 類）。辨識線索是 if 子句有 had + V3，而主要子句有 now, today, currently 等表示現在的字詞。

"Unless" 和 "if not" 完全一樣嗎？

大部分情況下 unless = if ... not：Unless you register, you cannot attend = If you do not register, ...。unless 之後用肯定動詞，不再加 not。不過 unless 的意思是「除非」，所以較少用於與過去事實相反的假設或表達情緒：I will be surprised if he doesn't come 就不能改成 unless。

"Should you have any questions" 是什麼意思？

這是第一類條件句的倒裝，等於 If you have any questions（如果您有任何疑問）。結構是 Should + S + 原形動詞，後半句通常是客氣的祈使句，例如 please contact。這個句型在多益的書信和公告中不斷出現，所以看到句首空格、後面接 you + 原形動詞 時，答案幾乎一定是 Should。