【问】 He____you more help，even though he was very busy.

A. might have given B. might give

C. may have given D. may give(全国高考英语试题，1990)

标准答案为A。但是我认为C(may have given)也是同样正确的。不知我的说法对否?

【答】 may have done与might have done都表示推测过去可能发生的事情，在这一点上，它们是同义的：

1. He may(might) have missed the train. (CGEL)

他可能没有赶上火车。

2. Before giving up completely，let’s look at the register. Someone may have changed hisreservation. Yes，here’s a telegram...You can have this gentleman’s room fortonight.(Nelson，300A)

暂时不要完全放弃，让我们先来看看登记薄。也许有人更改了预约。是啊，这有一封电报……你今天晚上可以住在这位先生的房间里。

下面的英语试题是更有力的证明：

1. You____John Marshall last year when you were in England. He is over two metrestall.

A. can have met B. may have met

C. can meet D. may meet (Nelson，250A)

2. Mary is very late. She____.

A. may miss her train B. may have missed her train

C. must miss her train D. could miss her train

但是，might have done还可表示“本该做而实际上并没有做”的意思。因此，根据上面试题的语义，应该选A(might have given)，而不应该选C(may have given)。参见may(might)have done，might。