def solve():
    n = int(input())
    s = list(input())

    stack = ['P', 'P']
    for idx in reversed(range(n)):
        if s[idx] == 'B':
            stack.append(s[idx])
        else:
            if stack[-1] != 'B':
                stack.append(s[idx])
            elif stack[-2] == 'B':
                del stack[-1]
            else:
                stack.append(s[idx])
        # print(stack)
    stack = stack[::-1]
    del(stack[-2:])
    print(''.join(stack))


t = int(input())
for i in range(t):
    solve()