n=int(input())
for _ in range(n):
    t = int(input())
    s = input()
    ans = []
    for i in range(t-1,-1,-1):
        ans.append(s[i])
        if len(ans) > 2 and ans[-3] == 'B':
            if ans[-1] == 'A' and ans[-2] == 'B':
                ans.pop()
                ans.pop()
    print(''.join(ans[::-1]))