Yao Ming might have carried the flag at the Opening Ceremony, but Liu is said to be China's most revered athletic hero.

【翻译】姚明本可以在开幕式上做旗手的，但刘据说是中国最受尊敬的体育英雄。

【分析】本句的might have carried 表示与过去情况不符的虚拟语气，意为“本可以怎样”。一般说来，情态动词would, might, could, should 都可以跟完成时连用，表示：1. 与过去不符的虚拟语气；2.对过去情况的推测

might have done 可以表达两种含义：

【虚拟语气】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。

【对过去的推测】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。

could have done：

【虚拟语气】If he had known the facts, he could have told us what to do. 如果他了解事实，他是可能告诉我们怎样做的。

【对过去的推测】Tom could have taken the money; he was here alone yesterday. 有可能是汤姆把钱拿走了，昨天他单独一个人在这里呆过。

注：表推测的could，多用于否定句或疑问句。

should have done:

【虚拟语气】

①I should have answered the letter yesterday, but it went right out of my mind. 我本该昨天回信的，但我把这件事忘得一干二净。

②But for the storm, we should have arrived earlier. 要是没有碰到暴雨，我们还会早到一些的。

【对过去的推测】

The train should have already left by then. 那时火车大概已经开走了吧。

would have done:

【虚拟语气】

表示虚拟语气，与过去情况不符或相反。

If we had had enough rain last year, we would have gained a good harvest. 如果去年雨水充足的话，我们会有一个好的收成。

这句话的含义是：去年雨水不足，我们粮食没有取得好收成。

She would have gone with me, but she didn't have time. 她本来会和我一起去的，但她没有时间。

【对过去的推测】

表示对过去事情的可能性推测。

People are recycling many things which they would have thrown away in the past. 现在人们都在回收他们过去可能会丢弃的东西。（2014安徽高考试题）

以上讲解说明：情态动词would, might, could, should 跟完成时连用，要么表示虚拟语气，要么表示对过去的推测。不可能用来陈述一个已发生的事实。如果真像你说的那样，我们就要怀疑这个句子的来历了。

【回复Expert】

may have done 不表示虚拟，只表示推测。