3 bet over pair preflop Ace hits on flop

[Kevin]

I can probably find about 50 examples inside of the PT database, but I wanted to ask a theoretical question.

Say a solid player raises early, you sit MP with a hand like JJ-KK. You 3 bet. all fold

an ace flops, he bets - assuming he is solid, what is the generally accepted action here?

What about if there are 2 loose passive/loose aggressive cold callers so 4 to the flop with an ace, solid bets, on you with 2 to act behind?

what about a solid raises early, 2 coldcallers, you sit in the small or big blind with QQ or KK and 3 bet. An ace flops - bet out? check call, check fold unimproved on 4th?

I am bleeding away alot of chips in these two scenarios. 3 bet , fold on the flop seems so weak, but it seems that I am looking at an AK, AQ, A...whatever, about 99.8% of the time.

Thanks,
Kevin

P.S.
If you want specific hands posted, I can find them and put them in the small stakes forum, but they all seem to be slight variations of the examples explained above.