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Hello,
I have one more question concerning the present perfect progressive.
When I say:
Sorry I am late. Have you been waiting long?
Why not "have you waited"? Because I am already there, so he or she is not waiting any longer.
Here, this past action has current relevance, importance. It would seem quite uncaring/rude to use "Did you wait for me long/Were you waiting long?"
Also, I'd say that the progressive form would be the more natural choice. Why? Not completely sure, but maybe it's because it adds a degree of nowness to the action
present perfect progressive once more 
Linear Mode
