mod = 998244353


def main():
    import sys
    input = sys.stdin.readline

    for _ in range(int(input())):
        N = int(input())
        S = input().rstrip('\n')

        T = []
        for s in S:
            T.append(s)
            while len(T) >= 3:
                if T[-3:] == ["A", "B", "B"]:
                    T.pop()
                    T.pop()
                    T.pop()
                    T.append("B")
                else:
                    break
        print("".join(T))


if __name__ == '__main__':
    main()