情态动词+完成时的语法意义（一）

有这样一个句子：Frederick William I, the king of Prussia, could never have imagined that his greatest gift to the Russian people would have such an amazing history. 普鲁士国王威廉一世绝不可能想到，他送给俄罗斯人民的厚礼会有这样一段令人惊讶的历史。句中could never have imagined表示什么含义呢？

在英语教学实践中，学生可能会碰到这样的问题：情态动词之后必须接动词原形吗？如果不是动词原形而是完成式，那么表达的意思是什么呢？

所谓的“动词原形”，指的是跟在情态动词后面的那个动词要用原形。事实上，情态动词后面的动词，除了原形以外，可用进行式、完成式等。例如：

She might be waiting for you. 她可能在等你。

You must have seen him. 你一定见过他了。

She may have missed her train. 她可能误火车了。

The door must have been locked by my wife. 门一定是我妻子锁的。

课本中，could have imagined即是“情态动词+完成时”结构，在这里表示对过去情况的推测。注意，原句用的是否定形式，表示“过去不可能发生的情况”（could never have imagined 意为“不可能想到”）。

本文拟对情态动词后用完成时的情况，以及所表达的语法意义，做一探讨和总结。

一、must have done的用法

must have done表示“对过去情况肯定的推测”。该结构只用于肯定句。意为“一定做过某事；肯定做了某事”。

Rosa must have attended the party last night.罗莎昨天晚上一定参加了晚会。

Angus must have read the book before.安格斯以前一定读过这本书。

It must have rained last night, for the road is all wet.昨晚一定下过雨，因为道路都是湿的。

【注意】英语中不存在must not have done的说法，must have done的否定式是can’t /couldn’t have done

二、may/might have done的用法

1. may/might have done表示“对过去情况不肯定的推测”，might的语气比may弱。

这种结构可以是肯定句，意为“可能做过某事”；也可以是否定句。意为“可能没有做过某事”。但不可以是疑问句，若表示疑问，则用Can/Could ... have done?

She may have read it in the papers. 她可能在报上已读到过此事。

They may not have known it beforehand.他们事先可能不知道这事儿。

You might have known about it from Mila.你可能从米拉那儿了解了此事。

He might have gone to have his hair cut. 他可能理发去了。

There might have been someone waiting outside. 可能曾有人在外面等候。

I’ll try phoning him, but he may have gone out by now. 我要给他打电话，但他现在可能出去了。

She may have missed her train. 她可能误火车了。

2. might have done 表示未曾实现的可能性

该结构仅限于使用might, 不用may。表示过去本来可以发生，而实际上没有发生的情况，即“过去本来可以做某事，而实际没有做”。通常译为“本来可以”，“本来可能”等。例如：

A lot of men died who might have been saved. 很多人本来可以获救的却死了。

He came home alone. You shouldn’t have let him do that; he might have got lost. 他独自回家了。你本不应当让他那么做的，他可能会迷路的。

You were stupid to try climbing up there. You might have killed yourself. 你从那儿往上爬，太蠢了，你可能会摔死的。

You might have phoned to let us know where you were. 你本来可以打个电话让我们知道你在哪。

有时，也可根据语境译为“好在没有”，“差点”，尤其是当谈论的是不利情况时。如：

It was really very dangerous. You might have injured him. 真是很悬，你差点把他打伤了

It was really very dangerous. I might have killed myself. 那真的是太危险了，我差点没命了。

3. might have done 除了含有上述的意思外，还表示批评或责备

即表示过去本来有责任或义务应该做某事的，但实际上却没有做成，含有批评和责备的意味，通常译为“本来应该”，“本来可以”等，用法同上。例如：

You might have let me know before! 你要是早点让我知道就好了!

She might have told me she was going to stay out all night. 她要是一夜不回来，应事先告诉我一声呀。

You might have taken the trouble to tell me the meeting was put off. 你本来可以费心告诉我一声会议推迟了的。

You might have told us half an hour ago. 你半个钟头前告诉我们就好了。

4. might have done用于虚拟语气

在虚拟条件句中，当谈论过去的情况时，其句型通常是：主句用“could/would/might +have+过去分词”，if从句用过去完成时。例如：

We might have arrived earlier if we had taken the other road.如果我们当时走了另一条路，就可能到得早一些。

If you had left it there, someone might have stolen it. 要是你当时把那东西落在那里，就可能有人把它偷走。

If the weather hadn’t been so bad, we might have gone out. 如果天气不是那么坏，我们可能都出去了。

I might have saved his life if I had found him earlier. 要是我那时早点找到他的话，我可能会把他救活的。

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