can + the Perfect Infinitive

[Li Chyan]

Hello!
I am interested in the meaning of the following grammar structure can+the Perfect Infinitive. Does it express incredulity or doubt?
e.g. Can he have read that note?
I'd also like to know the difference between can+the Perfect Infinitive and could+the Perfect Infinitive. Which of the two structures is used more often?
Thanks in advance!

[Cerberus™]

I don't think "can he have read" is ever used, it should be "could he have".
You use this when you ask about a possibility; it does not express doubt in normal contexts, it is a neutral question, although its probability is perhaps somewhat lower than that of a question like "is it possible that he...".

[Alan]

Hi Li Chyan,

If you take these two sentences:

Can he have misunderstood what you said?

Could he have misunderstood what you siad?

You can see two types of possibility. In the first you are asking whether it is possible and in the second you are asking whether it would be possible.

Alan
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