In the process of putting B into the magnetic field, it is not difficult to judge that there will be induced current in B according to Lenz's law, and if the N pole of A is upward and the direction of induced current in B should be clockwise from top to bottom, then C is correct and D is wrong; Because B is a superconductor and has no resistance, even if the electromagnetic induction disappears after B is stable, the current in B will not disappear, so B is right and A is wrong.

So choose BC.