beyond the realm(s) of possibility
Impossible. With my low test grades, I think that getting an A in this class is beyond the realms of possibility.
within the realm(s) of possibility
Possible; capable of happening. You worked so hard this semester that I think an A is within the realm of possibility.
beyond/within the realms of possiˈbility
impossible/possible: A successful outcome is not beyond the realms of possibility.