About inference of past

[Ju_n]

Hello, Teachers.

May I ask you a few questions?

Yes, first of all, I have big questions at this time.

1. " He can have said so. "
2. "He cannot have said so."

In my own dictionary, both sentences seem to right on grammar.

Also, in point of grammatical view,
it said "can + have + pp, cannot + have + pp" mean "the possible-ness about the past" as well as "may have + pp" (etc .

Although, I've almost nothing to hear of or see these sentence(especially 1st sentence I wrote) in my experience.

Then, so are these sentences really grammatically correct? And if so, they are useful
in native English?

If someone replies to my above two question, it would be great for me.

Thanks in advance.

Regards,


Jun

[Tdol]

We don't use the positive form can + have + past participle, but we do use the negative. When making assumptions, etc, we use the following patterns:
He must have said so. = I'm sure that he said so.
He can't have said so. = I'm sure he didn't say so
Yes, they are useful in native English- we often wish to express our degree of certainty about something.

[Ju_n]

Dear tdol

Thank you for your excellent answer as always!!!!
I was completely able to understand about that.

Hmm, it's just worth studying.Very interesting thing!

Thank you all the same!! tdol.


Best Regards,

Jun

[Tdol]

You're welcome, Jun.