John must have been a restless person.He kept moving from country to country.

A. must be

B. should be

C. must have been

D.should have been

     关于情态动词+have done用法归纳如下

【一】“must+have+done”表示对过去事情的肯定推测，译成“一定做过某事”，该结构只用于肯定句。
It must have rained last night, for the ground is wet.

昨晚一定下雨了，因为地面还是湿的。
You must have been mad to speak to the servant.

你和仆人说话，一定是发疯了。
【二】“can't+have+done”表示对过去事情的否定推测，译成“不可能做过某事”。
Mr. Smith can't have gone to Beijing, for I saw him in the library just now.

史密斯先生不可能去北京了，我刚才还在图书馆见过他。

Mary can't have stolen your money. She has gone home.

玛丽不可能偷你的钱，她回家去了。
【三】“can+have+done”表示对过去行为的怀疑，用于疑问句，译成“可能做过……吗？”。
There is no light in the room. Can they have gone out?

屋里没有灯，他们可能出去了吗？

There is nowhere to find them. Where can they have gone?

到处找不到他们，他们可能到什么地方去呢？

【四】“could+have+done”是虚拟语气，表示对过去事情的假设，意思是本来能够做某事而没有做。

He could have passed the exam, but he was too careless.

本来他能够通过考试，但是他太粗心。

【五】 “may+have+done”表示对发生过的事情的推测，意思是“可能已经”或“也许已经”，用于肯定句中。

—What has happened to George?
—I don't know. He may have got lost.
—乔治发生了什么事？
——我不知道，他可能迷路了。
【六】“might+have+done”表示对过去事情的推测，might与may意思相同，但可能性更小。多用于虚拟语气结构中。
He might have given you more help, even though he was busy.

他或许会多给你一些帮助，即使他很忙。

She might have achieved greater progress, if you had given her more chances.

如果你多给她点机会，她可能已经取得更大的成绩。
【七】 “would+have+done”虚拟语气，表示对过去事情的假设，意思是“本来会做”。

I would have told you all about the boy's story, but you didn't ask me.

我本来会告诉你这个小男孩的故事，但是你没有问我。
Without your help, I wouldn't have achieved so much.

没有你的帮助，我是不会取得如此大的成绩。
【八】 “should+have+done”意思是“本来应该做某事，而实际没做。” “shouldn't+have+done”表示本来不应该做某事，而实际做了。含有指责对方或自责的含意。

Tom, you are too lazy. The work should have been finished yesterday.

汤姆，你太懒惰了，这项工作本来应该昨天就做完的。

Look, Tom is crying. I shouldn't have been so harsh on him.

 看，汤姆哭了，我本来不应该对他如此严厉。
【九】“ought to+have+done”表示过去应该做而实际并没有做，译成“理应做……”，往往表示遗憾。与“should+have+done”用法基本一样。
I ought to have gone home last Sunday.

我理应上星期日回家。
You ought not to have given him more help.

你不应该帮助他那么多。
【十】 “needn't+have+done”则表示“本不需要做某事而做了”。

I needn't have bought so much wine—only five people came.

我本来没有必要买这么多酒，只来了五个人。

【十一】“need+have+done”表示本来需要做某事而没有

He need have hurried to the station. In that case, be wouldn't have missed the train.

他本来需要快点去车站，那样的话，他就不会误了火车。
【十二】would like to have done sth 本打算做某事
I would like to have read the article, but I was very busy then.

我本打算看这篇文章，但是我那时太忙了。
【十三】would rather +have done 当时宁愿做了 或没做
I would rather have refuse his offer

John        a restless person.He kept moving from country to country.

A. must be

B. should be

C. must have been

D.should have been

这道题测试情态 动词表示推测意义的用法。有两点需要注意。must和should都可以表示推测，must表示推测时，说话人的信心是百分之百，而should表示推测，说话人的信心只有60-70%。因此must翻译为”肯定”，should翻译为“应该、大概”。根据后一句话的一般过去时态，说话人是对过去的情况进行推测，情态动词后的不定式必须用完成体。一个人不停地从一个国家搬到另一个国家居住，由此推测这个人的性格，说话人的信心应该是很大的。因此选用must.最终的答案为C。