T = int(input())
for _ in range(T):
    N = int(input())
    S = list(input())
    S.reverse()
    
    A = []
    for i in range(N):
        if len(A) < 2:
            A.append(S[i])
        else:
            if S[i] == "A" and A[-1] == "B" and A[-2] == "B":
                A.pop()
            else:
                A.append(S[i])
    A.reverse()
    print(*A,sep="")