T = int(input())
for _ in range(T):
    N = int(input())
    S = input().strip()
    ans = []
    for i in range(N-1,-1,-1):
        a = S[i]
        if a=="A" and len(ans)>1 and ans[-1]=="B" and ans[-2]=="B":
            ans.pop()
        else:
            ans.append(a)
    print("".join(ans[::-1]))