import sys
sys.setrecursionlimit(10**6)

try:
    import pypyjit
    pypyjit.set_param('max_unroll_recursion=-1')
except ModuleNotFoundError:
    pass


def f(p, cs: list):
    if p == len(cs): return cs
    if cs[p] == 'C':
        cs[p] = 'A'
        return g(p+1, cs)

    return cs


def g(p: int, cs: list):
    if p == len(cs): return cs
    if cs[p] == 'A':
        cs[p] = 'B'
        return cs
    elif cs[p] == 'B':
        cs[p] = 'C'
        return f(p+1, cs)

    return cs


def solve():
    N = int(input())
    S = input()
    res = f(0, list(S))
    return ''.join(res)


INF = 1 << 60
T = int(input())
for _ in range(T):
    ans = solve()
    print(ans)