In the section "Complex anteriority: continuative and non-continuative perfects" of CGEL, there's this example given:
He may have told her last week. - Non-continuative perfect
Now, I'm confused. Some sources tell me to never (never to?) use specific time expressions like 'last week' with present perfect (with 'in the last week' being okay as in "I have seen that movie six times in the last week."), so am I to understand it as something else? Is "He have told her last week" also acceptable or must I use "He had told her last week" ?
Is it like a remote conditional where the apodosis verb must be a modal aux?
If the meeting finished on time, he may have caught the train