import sys

int1 = lambda x: int(x) - 1

# input = lambda: sys.stdin.buffer.readline()
input = lambda: sys.stdin.readline().rstrip()
ii = lambda: int(input())
i1 = lambda: int1(input())
mi = lambda: map(int, input().split())
mi1 = lambda: map(int1, input().split())
li = lambda: list(mi())
li1 = lambda: list(mi1())
lli = lambda n: [li() for _ in range(n)]

INF = float("inf")
mod = int(1e9 + 7)
# mod = 998244353

for _ in range(ii()):
    n = ii()
    t = []
    for c in input():
        t.append(c)
        while len(t) >= 3 and t[-3:] == ["A", "B", "B"]:
            t.pop()
            t.pop()
            t.pop()
            t.append("B")
    print("".join(t))