I am confused by this example:
"I haven't left France for three years:" "Je n'ai pas quitté la France depuis trois ans."
The lesson says "we use PC because the negation indicates the action wasn't done during the entirety of that past period. BUT PC is used to express actions which were completed or finished in the past.
This example shows it WAS NOT completed, so why PC and not imparfait??
Thank you.