Should "An bhfuil tú in ann an doras sin a dhúnadh?" have been accepted? And if not, why not? I'm having trouble figuring out when to use is féidir le x and when to use tá x in ann.
Yes, that should be equally acceptable.
Go raibh maith agat. I'll start reporting if I use one and get marked wrong because Duo wanted the other.
Someday I will remember to but an doras sin before a dhúnadh
what about "an bhfuil tú ábalta an doras sin a dhúnadh?"
Is that not ok?
My feeling is that it should be accepted. It conveys the necessary meaning of ability, and can be encountered in any of the dialects (and particularly in Ulster, I believe).