Chapter 8 情态动词
8.4 推测用法（三）：过去推测 （情态动词完成式）
8.4 推测用法（三）：过去推测 （情态动词完成式）
（一）
肯尼迪遇刺之谜
1963年11月22日，美国历史上最年轻的总统约翰·肯尼迪（John F. Kennedy）携同夫人杰奎琳参加完一次竞选活动后，来到得克萨斯州的达拉斯市。数声枪响之后，肯尼迪随之倒在了杰奎琳的膝上，从此告别了人世。
在事发后不到48小时，中央情报局就在达拉斯市抓获了一名犯罪嫌疑犯——李·哈维·奥斯瓦德（Lee Harvey Oswald）。但可疑的是，美国政府并没有对他提起诉讼，并且不久以后，这名刺杀肯尼迪的重要犯罪嫌疑人在众目睽睽之下被人枪杀。
1964年，美国政府就此案公布的官方调查报告《华伦报告》认定，奥斯瓦德是肯尼迪遇刺时唯一的凶手，他从得克萨斯州图书大楼向肯尼迪开了三枪。但15年后，美国众议院调查委员会重新对此案进行调查后得出结论称，当时刺客共向肯尼迪开了四枪，其中三枪来自图书大楼，另外一枪则来自另一个地点，这一结论进一步增加了人们对奥斯瓦德是单独作案的怀疑。
如今距离美国前总统约翰·肯尼迪遇刺已经有50多年，然而这场惊天谋杀案的真相至今仍迷雾重重。有调查显示，在过去的几十年里，关于肯尼迪遇刺的内幕至少有36种不同的版本，但至今没有一种版本真正令人信服，没有一种说法被证明属实。下面这篇短文就是人们围绕这个历史之谜所做的种种猜测：
On November 22, 1963, President John F. Kennedy, the thirty-fifth President of the United States, was assassinated in Dallas, Texas, while he was riding in an open car. Many people think it was foolish of him to be in an open car. He should have had a covered bulletproof car, as most world leaders do today. His death could have been prevented.
Immediately after the assassination, a suspect, Lee Harvey Oswald, was arrested. Two days later, as Oswald was being transferred to a jail, he himself was killed by a gunman in the crowd. An investigation took place to find out the truth behind the assassination. After examining a lot of evidence and questioning many people, the investigating committee determined that Lee Oswald must have been the person who shot Kennedy. However, many theories have been made about why he did it. Some people think Oswald could have been a crazy person who thought he could get attention by killing a famous man. Another theory states that he might have been the agent of another government, possibly Russia or Cuba. According to another theory, organized crime (the Mafia) may have been behind the assassination.
Some witnesses report gunshots coming from two different directions. If this is true, Oswald could not have acted alone; there must have been more than one gunman.
Even though the assassination occurred many years ago, people are still fascinated with this event. Books and movies have appeared through the years offering new theories about this mysterious tragedy. Because Oswald was killed before he went to trial, many questions have remained unanswered.
上文中黑体部分的句子除了前两个句子（should have had, could have been prevented）外，其他的都是表示对过去的推测。比如：
1 The investigating committee determined that Lee Oswald must have been the person who shot Kennedy.
2 Some people think Oswald could have been a crazy person who thought he could get attention by killing a famous man.
3 Another theory states that he might have been the agent of another government, possibly Russia or Cuba.
4 According to another theory, organized crime (the Mafia) may have been behind the assassination.
5 If this is true, Oswald could not have acted alone; there must have been more than one gunman.
由以上例句我们看到，表示对过去的推测，英语的谓语形式要用“情态动词完成式”，常用的情态动词有must，may，might和could，所以要说成 must have been, may have been, might have been和could have been等形式；若是在否定句中，则需要将must换成can或could，说成can’t have done或couldn’t have done，比如上文中的could not have acted。显然，表示对过去的推测的谓语形式与上一节中所讨论过的表示对现在的推测的谓语形式“情态动词一般时态”不同，这一点请读者一定要注意。所以，在上述表示过去的场景中，所做的推测就不能这样表达：
The investigating committee determined that Lee Oswald must be the person who shot Kennedy.*
Some people think Oswald could be a crazy person who thought he could get attention by killing a famous man.*
Another theory states that he might be the agent of another government, possibly Russia or Cuba.*
According to another theory, organized crime (the Mafia) may be behind the assassination.*
If this is true, Oswald could not acted alone; there must be more than one gunman.*
其中情态动词所表达的推测的确定程度与对现在的推测中所说的一样，即must表示非常确定的推测，may其次，might或could最不确定。比如：
6 A: Why wasn’t John in class yesterday?约翰昨天怎么没来上课？
B: He was sick.他病了。
He must have been sick.他一定是病了。
He may have been sick. 他可能病了。
He could/might have been sick. 他或许是病了。
（二）
虚拟还是推测？
另外值得注意的是，上文中前两个黑体的句子：
7 He should have had a covered bulletproof car, as most world leaders do today.
8 His death could have been prevented. 他（约翰·肯尼迪总统）也就不会丧命了。
根据对上下文的分析，这两句话并不是表示对过去的推测，而是表示与过去事实相反的假设，即表示对过去的虚拟。事实上，英语中四个过去形式的情态动词would，could，might和should既可以表示推测，也可以表示虚拟。具体来说，would/could/might/should do可以表示对现在或将来的推测，也可以表示对现在或将来的虚拟；would/could/might/should have done可以表示对过去的推测，也可以表示对过去的虚拟。请比较例句：
9 1） I don’t know who killed John, but I guess his wife Mary could have killed him.
2） You could have killed me, I hope you know.
妙语点睛 在例句1）中，根据上下文语境可知，could have killed是表示对过去的推测，“玛丽杀死自己丈夫约翰”存在一定的可能性。在例句2）中，根据上下文语境可知，could have killed是表示对过去的虚拟，事实上“我”没有死，即不存在“我过去死”的可能性。
所以，对于某些谓语带有would，could，might和should的句子，在没有具体语境的情况下，可能会在“推测”与“虚拟”之间产生歧义。比如：
10 He could have sent a message.
这个句子既可以理解为对过去的虚拟，译成：他本来可以事先捎个口信过来的（但实际上没有这么做，表示抱怨）。
也可以理解成对过去的推测，译成：他可能已经捎口信过去了。
再如：
11 He might have been drowned.
当然，如果我们说：
12 You might have been drowned!
妙语点睛 因为主语是you，所以这句译成虚拟的意思较为妥当。
再如：
13 You shouldn’t have drunk that wine. You might have been drugged.
妙语点睛 这里有两处采用了“情态动词完成式”的结构：shouldn’t have drunk和might have been drugged。该如何理解这两句话的意思呢？其实同样存在“虚拟”与“推测”之间的歧义：如果是虚拟，则可以理解成“你不应该喝那酒，要是里面放有迷药把你迷倒了怎么办”，而实际上酒里没有迷药。这反映了说话人一种事后的担心和后怕，言外之意是告诫听话人以后不要乱喝酒。如果是推测，则可以理解成“你不应该喝那酒，你可能已经被其中的迷药迷倒了”。若这么理解，表明此时“你”已经出现了被迷药迷倒了的症状，于是说话人推测可能是因为“你”喝的那酒造成的。
对于读者非常熟悉的should have done句型，一般会被理解成“本来应该做，但实际没有做”。比如上面这个例句中的shouldn’t have drunk就是表示虚拟，意思是“你本来不应该喝那酒，但实际上你已经喝过了”，这其实是它的虚拟含义。不过，我们也可以用它来表示对过去的推测，表示说话人所希望发生的事。请比较：
14 1） You should have received four letters by now.
2） I should have received four letters from them, but I got none.
妙语点睛 在例句1）中，说话人是在推断说“到现在你们应该收到过四封信”，他用should来表示非常确定的推测，言外之意是，如果不出意外，四封信应该已经在你们手里了。当然，也许会出现万一的情况，导致你们没有收到来信。这就是should的推测用法：很可能收到了信，也可能没有收到。在例句2）中，说话人是在用虚拟语气抱怨说“我应该收到他们的四封信，但实际上我一封也没有收到”。这里的should表示虚拟，就不像例句1）中的推测那样存在“很可能收到了信，也可能没有收到”这两种可能性，而只有一个现实：我一封信都没有收到。
请看例句：
15 The letter should have arrived by now. 我相信现在该到了。
16 He should have finished by now. 他现在该完成了。
建议读者结合第七章“虚拟语气”中讨论的内容来比较would，could，might，should do/have done可能出现的推测或虚拟的歧义。我们可以这样来分辨是推测还是虚拟：知道确切结果的是表示虚拟，而不知道确切结果，即存在两种可能性的是表示推测。结合这一点，请读者再看看上面例句的意思。
现在形式的情态动词must，can，may和will不能表示虚拟，所以must/can/may/will have done只能是表示对过去的推测，而不能表示对过去的虚拟。
请看下面这篇小短文，这是我的一个澳大利亚朋友讲述自己在中国湖北孝感任教的经历时说的一番话。这位朋友虽然是澳大利亚人，但他的大部分时间都是在其他国家度过的，足迹遍布了世界各地。但不知出于什么原因，他觉得到了中国之后，有一种回家的感觉，所以他在文中说“我上辈子一定是一个中国人”：
17 My year in China turned out to be one of the most memorable periods in my varied life. I sometimes thought I must have been born a Chinese in a past life because I felt more at home in China than any of the other countries where I lived.
My one regret was that my wife hadn’t been able to come with me because I know she would have liked the whole experience as much as me.
I suspect there may have been an element of luck in being reassigned to Xiaogan rather than Chengdu but, for whatever reason fate took a hand, it proved to be a really marvelous experience.
妙语点睛 我们看到，上文中三处黑体的句子分别用了must have been, would have liked和may have been“情态动词完成时态”的形式，其中must have been和may have been表示的就是对过去的推测，而would have liked则是表示对过去的虚拟，因为他的夫人当时没有和他一同来中国，所以说她…liked the whole experience as much as me只能是一种假设。
我们再看看下列场景中对过去推测的表达：
18 A: I must have lost some weight. Look, how baggy my pants are. 我准是瘦了不少，你看我这裤子多肥。
B: They don’t look that loose to me. 可是我看它并不显得那么肥。
19 A: Why are the windows open? 窗户怎么是开着的？
B: A burglar must have broken in. 一定有贼闯进来了。
20 A: The money has disappeared! Who could have taken it? 钱没了！会是谁拿的呢？
B: John could have (taken it); he was here alone yesterday. 可能是约翰，他昨天一个人在这里。
21 Oh no, a traffic jam. There must have been an accident. 哦，又是堵车，一定是发生交通事故了。
22 The guests will/would have arrived by that time. 到那时，客人将已经到了。
23 They might not have received our letter yet. 他们或许还没有收到我们的信。
24 I suppose I may have been rather critical. 我想我当时可能是太苛刻了。
另外需要提醒大家注意的是，“情态动词have done”的结构不一定相当于现在完成时。例如：
25 You must have seen him. （你一定见过他了。）
可以相当于：
I assume now you have seen him before.
I assume now you saw him last night.
I assume now you had seen him before you came here.
我们看到，在must have seen这个结构中的have seen，在时间上可以相当于一个现在完成的动作have seen，也可以相当于一个过去的动作saw，甚至可以相当于一个过去完成的动作had seen。
思维总结
本节重点讨论了情态动词对过去的推测的结构和用法。首先，读者需要掌握，表示对过去的推测，需要用“情态动词完成式”这一结构。这里的情态动词既可以是现在形式的may，can和will，也可以是过去形式的might，could，would和should。
但是，对于过去形式的情态动词could，might，would和should，在没有具体语境的情况下，可能会在“推测”与“虚拟”之间产生歧义。建议读者结合第七章“虚拟语气”中讨论的内容来比较would，could，might，should do/have done可能出现的推测或虚拟的歧义。我们可以这样来分辨是推测还是虚拟：知道确切结果的是表示虚拟，而不知道确切结果，即存在两种可能性的是表示推测。
思维训练 8.4 Key
一、请用动词的适当形式填空，以表示推测语气，注意确定程度的不同。
1. It rained every day during their holiday, so they ______ （not/have） a very nice time.
2. The restaurant ______ （be） very good. It’s always full of people.
3. The phone rang but I didn’t hear it. I ______ （be） asleep.
4. There ______ （be） a bad accident here. Look at all the broken glass.
5. Jane walked past me without speaking. She ______ （not/see） me.
6. Joe isn’t at work today. He ______ （be） ill.
7. Joe wasn’t at work last week. He ______ （be） ill.
8. When I woke up this morning, the light was on. I ______ （forget） to turn it off.
9. The lights were red but the car didn’t stop. The driver ______ （not/see） the red light.
10. She knew everything about our plans. She ______ （listen） to our conversation.
11. I can’t find my umbrella. I ______ （leave） it in the restaurant last night.
12. I left my bike outside the house last night and this morning it wasn’t there any more. Somebody ______ （take） it.
13. A: He says he saw you at the theater yesterday.
B: He ______ （not see） me. I wasn’t there.
14. A: He has been working the whole morning.
B: He ______ （be） very tired.
15. A: Did you hear me come in last night?
B: No, I ______ （be） asleep.
二、请判断下列句子是否有虚拟意义，并用may或can’t来改写句子。
16. I could have left my office keys at home because I can’t find them anywhere.
17. I could have married anybody I wanted to.
18. Jim started smoking last year. He might have picked up this bad habit from his friends.
19. It’s a pity you didn’t ask because I could have helped you.
20. The letter might have arrived by now.
21. You could have helped me!
22. You could have received four letters by now.
23. Your mother could have called when you were out.
24. You might have left your umbrella in the restaurant.
25. You screamed in your sleep last night. You might have had a terrible dream.
26. You might have drowned!
27. I suppose I might have been rather critical.
28. They might not have received our letter yet.
29. Some women could have made a good salary in a job instead of staying home, but they decided not to work for the sake of the family.
30. I could have become a millionaire, but I decided not to.
31. I can’t find my sunglasses. I might have left them at the restaurant yesterday.
32. I don’t know who rang, but it could have been Jim.
33. I could have bought that car, but I decided to look at a few others.
34. Peter wasn’t here, so he couldn’t have broken your vase.
35. The test was no problem at all. It couldn’t have been easier, in fact!
36. The package is gone. Someone could have picked it up by mistake.
37. A: Donna, you said you’d take this package to accounting yesterday.
B: Oh, no. It could have slipped my mind.
38. A: Why are the windows open?
B: A burglar might have broken in.
39. A: It took me five days to drive down to Florida.
B: Five days? I could’ve walked there in less time.
40. A: I haven’t seen you like this in weeks.
B: The committee finally reached a decision, and I couldn’t have hoped for a better outcome.
41. A: I could have seen this play five times. Don’t you think it’s great?
B: Not that great.
42. A: I might have lost some weight. Look how baggy my pants are.
B: They don’t look that loose to me.
43. A: I’m sorry I missed your soccer game. But I had the flu.
B: Don’t worry about it. We couldn’t have played worse.