由以上例句我们看到，表示对过去的推测，英文的谓语形式要用“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，could have been，might have been和may 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不同于在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”，这一点请读者朋友一定要注意。所以，在上述表示过去的场景中，所作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肯定程度与对现在的推测中所说的一样，即must表示非常肯定的推测，may其次，might或could最不肯定。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，上文中前两个黑体部分的句子：

7　He should have had a covered bulletproof car, as most world leaders do today.

他（约翰·肯尼迪总统）应该像如今的各国政要那样，乘坐封闭的防弹汽车才对。

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，而是表示一个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，根据上下文语境知道，could have killed是表示对过去的推测，“玛丽杀死丈夫约翰”存在一定的可能性。在例句2）中，根据上下文语境知道，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。

精品译文

1）我不知道是谁杀死了约翰，但我猜测他的妻子玛丽可能杀了他。

2）你差点要了我的命，我希望你知道这一点。

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，因而可译成：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，因而可译成：他可能已经捎口信过去了。

再如：

11　He might have been drowned.

精品译文

译文1：他当时差点就淹死了（虚拟）。

译文2：他可能已经淹死了（推测）。

当然，如果我们说：

12　You might have been drowned!

妙语点睛

此时，因为主语是you，所以，这句译成虚拟的意思较为妥当。

精品译文

你当时差点就被淹死了！

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。

精品译文

译文1：你不应该喝那酒，要是里面放有迷药把你迷倒了怎么办（虚拟）。

译文2：你不应该喝那酒，你可能已经被其中的迷药迷倒了（推测）。

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的，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来表示非常自信的推测，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：信很可能收到，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“信很可能收到，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。

精品译文

1）到现在你们应该收到过四封信。

2）我应该收到他们的四封信，但实际上我一封也没有收到。

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。

建议读者结合在第七章“虚拟语气”中讨论的内容来比较would，could，might，should do/have done可能有的推测或虚拟的歧义。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，请读者自己回头再看看上面例句的意思。

但是，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，这是笔者的一个澳大利亚朋友在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，自己有一种回家的感觉，所以他在下文中说“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这种“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。

精品译文

我在中国一年的任教经历，是我这辈子丰富人生经历中最值得回味的部分。有时我就想，我上辈子一定是一个中国人，因为在我所生活过的国家中，中国让我感觉更像回家。

我唯一的遗憾是，我的夫人当时并没有和我一同去中国，要不然，我想她一定也会和我一样热爱中国的。

我本来是要去成都任教的，但后来被分配到湖北孝感，这好像冥冥之中有命运在安排，但不管怎样，这段经历最让人难忘。

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，你看我穿这裤子现在显得多肥。

B: They don't look that loose to me. 可是我看它并不显得肥。

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一个现在完成时。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推测过去的结构和用法。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和could以及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。建议读者结合在第七章“虚拟语气”中讨论的内容来比较would，could，might，should do/have done可能有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

Exercise 8.4

请用动词适当形式填空，以表示推测语气，注意肯定程度的不同。

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.

请判断下列句子是否有虚拟意味，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.





8.5　推测用法（四）：情态动词＋（完成）进行式

在8.1.3小节讲过，情态动词接完成式、进行式及完成进行式，此时的情态动词均是表示推测的含义。所以，情态动词与进行式或完成进行式连用时，表达的意思与相应的进行时态或完成进行时态的意思差不多，只是增加了情态的意义——推测含义。比如：

1　I can't reach my friend. His line is always busy. He might be using the Internet now.

这里是说，“我”打电话找我的朋友找不到，电话总数占线，于是“我”就推测他现在可能正在上网，所以占用了电话线。如果“我”是很确信他在上网，那就可以说成：

He must be using the Internet now.

或者不是很确信地说：

He may be using the Internet now.

当然，如果知道他确实就在上网，则可以不用情态动词，而直接用现在进行时态说成：

He is using the Internet now.

从以上的例句我们看到，“情态动词＋进行式”同一般进行时态一样，表达的是一个现在正在进行的活动，只是因为有了情态动词而增添了情态的意义——推测含义。

在《老友记》（Friends）中有这样一个场景：罗斯（Ross）的前妻凯萝尔（Carol）要临产了，罗斯、雷切尔（Rachel）、钱德勒（Chandler）、乔伊（Joey）和莫尼卡（Monica）等众人在医院的休息室里等候凯萝尔和她的同性恋女友苏珊（Susan）的到来。罗斯见她们迟迟未到，焦急地说道：

2　She's not here yet. She's not here. She's having my baby and she's not here. God, I don't believe this. She could be giving birth in the cab.

妙语点睛

这里罗斯说could be giving即是情态动词接进行式，表示在说话的时刻可能发生的事件。我们也看到，这里罗斯用了最不肯定的词could，一方面表明他不希望他的前妻在出租车上生孩子这件事真的发生，另一方面也说明了他的焦急程度——急得如此胡思乱想！如果他希望这件事发生，他就会用should了。

精品译文

她还没有到，她还没有到，她就要生下我的孩子了，可她现在却还没有到。天啊，真不敢相信。她现在或许正在出租车上生产了。

我们再来看其他例句：

3　A: Congratulations! I understand you got a job. When do you start work?

B: You must be thinking of someone else. I'm still waiting to hear.

A：恭喜你！我知道你找到新工作了，什么时候开始上班啊？

B：你想的一定是别人，我还在等着听信呢。

4　I am afraid he hasn't found a job yet. He must still be checking the papers.

我恐怕他现在还没有找到工作，他一定还在翻着报纸找呢。

5　The plane should be landing now. 飞机现在肯定在降落。

6　They can't be having dinner right now. 他们现在不可能还在吃晚饭。

“情态动词＋进行式”也可以用在虚拟语气中。比如下面这个面试的场景：

7　A man is applying for a job. Here is the talk between the director and him.

Director: What's your name, please?

Man: Greg Bulmash.

Director: What's your favorite position?

Man: Whatever's available. Well, if I were a picky person, I wouldn't be applying here in the first place.

Director: What salary do you expect?

Man: $ 185,000 a year plus stock options and a long vacation.

精品译文

一个人应聘一份工作。下面是公司主任与他的谈话。

主任：请问您的名字？

应聘者：格雷格·布尔马什。

主任：您最喜欢的职位是什么？

应聘者：什么职位都可以。我要是个很挑剔的人，我现在就不会在这里申请工作了。

主任：你期望的薪水是多少？

应聘者：年薪18.5万美元，外加股票期权和带薪长假。

我们再来看看情态动词与have been doing连用的情形。请看例句：

8　A: Oh, I must have been sitting in the same position too long. My legs have fallen asleep.

B: Shake it a little before you get up.

妙语点睛

这里must的后面接完成进行时表示推测，而且这里的完成进行式就相当于一个现在完成进行时态have been sitting，表示一直持续的一个动作或状态。

精品译文

A：噢，我一定是同样一个姿势坐得太久了，我的两条腿都麻了。

B：站起来之前，你先把腿甩甩。

请看其他例句：

9　You must have been dreaming. 你刚才一定是一直在做梦。

10　You can't/couldn't have been swimming all day. 你不可能一整天都一直在游泳。

“情态动词＋完成进行式”也可以用在虚拟语气中。比如：

11　You shouldn't have been following him so closely; you should have kept your distance.

你本不该一直跟着他那么近，你应该和他保持一定的距离。





8.6　基本用法（一）：现在或将来的能力

本节开始讨论情态动词的基本意义和用法。首先，来讨论读者非常熟悉的一个基本意义——能力。

说到表示“能力”的情态动词，相信很多读者立即会想到can。能这么联想自然没错，不过，如果把can与“能力”完全等同起来，那就不对了。原因有二：首先，can的含义远不止“能力”这一个意思；其次，即使是表示“能力”，这个“能力”又该如何理解呢？

看到这里，很多读者也许开始纳闷了：“能力”就是“能力”嘛，这还需要有什么过多的解释吗？

其实不然，英语表达的“能力”和汉语是有差别的，而且差别很大，以至于需要通过本节以及接下来的8.7和8.8共三节的内容来详细讲解。只有这样，读者才能真正明白英语的“能力”的含义。