def solve():
  N=int(input())
  S=input()[::-1]
  Q=[]
  for i in range(N):
    Q.append(S[i])
    if len(Q)>=2 and Q[-1]=='A' and Q[-2]=='B':
      if len(Q)==2:
        continue
      if Q[-3]=='B':
        del Q[-1]
        del Q[-1]
  print(''.join(Q[::-1]))

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