from collections import deque

t = int(input())
for _ in range(t):
    n = int(input())
    S = input()
    ANS = deque()
    for i in range(n - 1, -1, -1):
        ANS.appendleft(S[i])
        if len(ANS) > 1 and ANS[0] == 'A' and ANS[1] == 'B':
            if len(ANS) > 2 and ANS[2] == 'B':
                ANS.popleft()
                ANS.popleft()
    print(''.join(ANS))