Hello
Please look at the sentence below:
1.If you hurry,you will overtake him.He has only just left here and CAN’T HAVE GONE far.
I think the action ‘‘can’t have gone’’ implies a past action just like the use of other modal verb ‘‘must have gone’’ or ‘‘might have gone’’ but in the context here it implies a present action.
Please explain it for me (I forget to type question :D)
Can’t have gone means incredulity, improbability (It’s hardly possible that, I refuse to believe that, etc.). It doesn’t matter if you use can’t or couldn’t in this meaning. Perfect Infinitive is used to denote past, of course. And the context proves it. It shows what place the person reached/arrived at/got. - this is what I think about it 
Hi,
It doesn’t matter whether it is in present or past - who actually cares? What is important is whether you understand it or not. Think about it.
Regards
To SkiIucK ,If it is important whether you understand it or not , how about when you want to talk about the same action and context ? 
How can you do to make people understand you ?
And I want some more help ,please ?
From Then (when he left) to Now (when we are speaking), he can’t have gone far.
The present perfect is a present aspect/tense. Above, we ask “where IS he at THIS moment”. There, the present perfect is being used in its resultative sense.
But as far as I know ,when perfect infinitive goes with modals, it indicates a past action.But is it true that it depends on the context to understand ?
The action he has gone is in the past. (or he hasn’t gone far, or he can’t have gone far).
If it were in present you’d have He can’t go far = he is not able, though it sounds awkward.
.
I might interpret ‘He [color=blue]can’t [color=green]have gone far’ this way:
‘It just [color=blue]isn’t possible that he [color=green]has gone far’.
.
Not sure who is arguing that the going was not in the past. Who is?
Or “it is not possible that he IS far (away)”.
Present perfect: Used to relate events or states taking place in the past to a present time orientation.
The present perfect represents a secondary past in the present, and thus references both a primary present and a secondary past relative to it. The narrative time is present [the sentence is about the present], but the event time of the sentence is past.
From: A COURSE IN ENGLISH GRAMMAR by
Michael Noonan
Agree on all explanations. This one:
I like most of all. 
But is it clear for duc?
Maybe duc needs to go back to the basics of using the present perfect and modals.
Thank you very much!
After reading your ideas,I have made it out very clearly You are true Molly I have just read Modal+perfect infinitive in the Longman grammar and now I understand it.
Again thanks ,my teachers !
Well done, Duc. 8)