未來完成式例句用法解析
未來完成式是多益考試常考但多數學生比較不熟悉也不常應用於日常生活中的時態，完成式的核心概念是表達在某個時間點之前已經完成某事，「未來完成式」簡單地來說就是用來表達截止到「未來」的某個時間點之前已經完成的活動，英文句構上會用「will have + past participle過去分詞」來表示，但這樣講畢竟還是很抽象，接下來我將以日常生活例句及時間軸圖解析未來完成式的使用情境，並附上未來完成式單獨的練習題及三個完成式混合在一起的練習題，希望能幫大家輕鬆掌握現在完成式、過去完成式和未來完成式的用法。
未來完成式例句用法
用法一: 表達未來某一個時間點之前已經完成的事情
例一:
I will finish the project at 4:30.
My friend will come at 5:30.
By the time my friend comes, I will have finished the project.
我將在四點半時完成專案，我的朋友將在五點半時來拜訪我，在我朋友來之前我將已經完成我的專案了。在這個情境中兩件事情都發生在未來，要表達這兩件事情的先後順序，先發生的用未來完成(will have + P.P.)，後發生的用現在簡單式。在上述例子中。如果只是單單描述未來的某個時間點發生的事情都用未來簡單式來表達: I will finish the project at 4:30. My friend will come at 5:30. 但是當我想要表達「在我朋友來之前我已經完成專案」，先發生的事情(我已經完成專案)就會用未來完成式表達，而後發生的事情(My friend will come)因為是一個時間副詞子句，需用現在簡單式來表達未來的文意(此一概念請詳見文章"未來簡單式未來進行式一次搞定")。
例二:
My teacher gave us a lot of homework in class.
I will have finished my homework by next Friday.
今天老師在課堂上給我們很多作業，在下周五之前我將會已經完成我的功課了。在此情境中，我在老師指派作業後開始做作業，然後在下週五這個屬於未來的時間點，我想強調將會「已經做完」功課這件事情，故用未來完成式表達。
例三:
I have watched this video three times.
If I watch this video once more, I will have watched it four times.
如果我再看這個影片一次，我將會已經看它四次了。在這個例句中，我在「現在」這個時間點之前已經把這支影片看了三次了I have watched this video three times.如果我再看一次影片的話(這件事是我未來可能會去做的事情)，If子句用現在簡單式表達，我將會已經看這支影片四次了，主要子句用未來完成式表達。簡言之在此例句中，我想表達截至未來某個時間點之前某活動已經完成並重複過的次數，便會用未來完成式來表達。
用法二: 持續到未來某個時間點的狀態或動作
未來完成式用於表達截至未來某個時間點之前已經持續一段時間的動作或狀態，這個狀態或動作開始的時間點可能是起始於過去並一直持續到未來，另外，表達持續到未來某個時間點之前已經持續一段時間的動作亦可用未來完成進行式。
例一:
I will go to England in November and stay there.
My friend will visit me in England in December.
When my friend visits me, I will have been in England for a month.
我將會在11月時去英國，我朋友將在12月時去英國拜訪我，當我朋友來英國拜訪我時我將會已經在英國待上一個月了。在這個情境中，我將在11月去英國和我朋友將在12月時去英國拜訪我，這兩件事情都發生在未來，單純描述在未來的某個時間點發生的事情都用未來簡單式表達，但當我想表達當我朋友12月來拜訪我時，我從11月持續到12月都在英國整整待上一個月的狀態時，「當我朋友來拜訪我時」這個句子因為是時間副詞子句會用現在簡單式，主要子句「我將會已經在英國待上一個月了」會用未來完成式來表達。
例二:
I started teaching English in September 2011. It’s 2020 now.
I have been teaching English for nine years.
(I have taught English for nine years.)
By September 2021, I will have taught English for ten years.
(By September 2021, I will have been teaching English for ten years.)
我在2011年9月開始教英文，這件事起始於過去，並一直持續進行到現在這個時間點，我已經教英文教9年了，此句用現在完成式或現在完成進行式表達; 但如果教英文這個動作是一直持續到2021年9月，2021年9月是未來的時間點，我將會已經教英文教10年了，此句會用未來完成式或未來完成進行式表達。
例三:
My parents got married on October 25, 1983.
Today is October 10, 2020.
By October 25, my parents will have been married for 37 years.
我的父母在1983年10月25日結婚，注意這件事情也是起始於過去，今天是2020年10月10日，到今年2020的10月25日，我父母將會已經結婚37年了，截至到未來的時間點10月25日，我父母結婚這個狀態已經持續了37年，這句話用未來完成式表達。
用法三: 對過去可能發生過的動作的推測(express certainty about the past)
我們可以用will來表達現在或未來可能發生的事情的推測，例如：
Someone is ringing the doorbell. That will be Winnie.
某人正在按電鈴，那應該是Winnie。
Don’t call Grandmother right now. She will be sleeping.
現在別打電話給祖母，她應該正在睡覺。
Tomorrow will be windy.
明天將會是多風的天氣。
但如果是推測對過去可能發生過的動作，會用未來完成式will have + P.P. 表達，例如:
As you will have noticed, there are some new employees in the headquarters.
如同你已經注意到的，在總公司有一些新員工。這邊推測對方過去已經注意到這件事情，所以用未來完成表達。
It’s no use running-- the train will have left by now.
現在跑也沒用了，火車應該已經開走了。推測火車在過去已經開走。
We can’t go to the library now-- it will have closed.
現在不能去圖書館了，它應該已經閉館了。 推測圖書館在過去已經閉館。
未來完成式練習題
依照情境填入未來完成式或現在簡單式正確的動詞型態
1. Susan will finish her homework at 3 o’clock. She will go out on a date at 7 o’clock. By the time she ____________ (go) out on a date tonight, she ___________ (finish) her homework.
2. There is no use hurrying. By the time you ____(get) to the airport, the airplane _________(take off).
3. If I read this novel once more, I __________(read) it seven times.
4. The project has been assigned to Jason today. He ________________(finish) the project by the time he ____________(make) a presentation.
5. Peter _________(take) the TOEIC test ten times if he ______(take) it once more.
6. They have known each other for a long time. By next month, they ____________(know) each other for more than 20 years.
7. I visited my friend in Arizona two weeks ago. I am staying with them now. By next week, I _______________(stay) with them for three weeks.
8. On the third of next month he __________________(be) in hospital for two weeks.
9. You _____________(hear) that I am going to work in Japan next month.
10. Dear Miss Lucy, you ____ recently ___________(receive) a contract about the publication of your new book.
11. The traffic is heavy. We are going to be late. By the time we _______(arrive), the concert ____________(begin) and Michael will be wondering where we are.
12. You must be kidding! He got another dog? At this rate, he _________(have) a dozen dogs by the time he __________(graduate).
答案:
1.goes out, will have finished
2. get, will have taken off
3. will have read
4. will have finished, makes
5. will have taken, takes
6. will have known
7. will have stayed
8. will have been
9. will have heard
10. will...have received
11. arrive, will have begun
12. will have had, graduates
三個完成式混合練習題
請依照情境選擇正確的時態
1. Bill ________ to have cats until he met the brown cat Zongma. After the cat won his heart, he began to help stray cats find homes. A) doesn’t want B) hadn’t wanted C) will not have wanted D) hasn’t wanted
2. Since I left the United States ten years ago, I __________to visit my teachers and friends several times. A) return B) will have returned C) am returning D) have returned
3. Lily, _______since you got home from the fitness center?
A) have you taken a shower B) will you have taken a shower C) are you taking a shower D) do you take a shower
4. By the time the kittens leave their mother, they ___________how to hunt.
A)will learn B) had learned C) will have learned D) have learned
5. I adopted my cats on January 21st. Today is January 28th. I ________my cats for a week. A) have adopted B) had adopted C) will have adopted D) adopted
6. I adopted my cats on January 21st. Today is January 28th. By 24th, my cats
_________at my home for three days. A) have been B) had been C) will have been D) are
7. I adopted my cats on January 21st. Today is January 28th. By February 21st, my cats _________at my home for a month. A) have been B) had been C) will have been D) are
8. By the time Wendy returns to her hometown, she _________away from home for more than twenty years. A) is B) has been C) had been D) will have been
9. Jay wants to start his own business, but he __________enough money yet. A) hasn’t had B) hadn’t had C) will not have had D) doesn’t have
10. By the end of the 21st century, scientists _____________the cure for this incurable disease. A) have discovered B) had discovered C) discovered D) will have discovered
答案:
1. BDACA 6. BCDAD
未來完成式常見問題
未來完成式公式?
未來完成式的公式是will have + past participle過去分詞
未來完成式用法?
未來完成式用來表達截止到「未來」的某個時間點之前已經完成的活動，例如: I will have finished the project by next Friday. 在下周五之前我將會已經完成這個專案
未來完成式被動?
未來完成式被動will have been + past participle過去分詞
例如: 主動的句子是Jay will have finished the project. 改成被動式就變成The project will have been finished by Jay.
未來完成式與未來完成進行式?
未來完成進行式的公式是will have been +V-ing 例如:By next year, I will have been teaching English for 12 years. 截至到明年我將會已經教書12年了，當然這句話也可以用未來完成式表達I will have taught English for 12 years by next year. 文意是一樣的，但是如果今天用的動詞是非動作動詞或表達截至到未來已經完成的動作(此動作沒有在持續進行)則只會使用未來完成式，例如: By the time my newphew sees me, he will have been two years old. 下次我侄兒見到我時，他將會已經兩歲了If I read this novel once more, I will have read it three times. 如果我再讀一次這本小說，我將會已經讀它三次了。
參考書目:
Azar, Betty Schrampfer.Understanding and Using English Grammar. 3rd ed. New York: Pearson Education, 1999.
Swan, Michael. Practical English Usage.3rd ed. Oxford: Oxford UP, 2005.
柯旗化。New English Grammar新英文法。高雄市: 第一出版社。
