import sys
input=lambda:sys.stdin.readline().rstrip()
def solve():
	N=int(input())
	S=input()
	ans=['A']
	for i in range(N-1,-1,-1):
		ans.append(S[i])
		if len(ans)>2 and ans[-3:]==['B','B','A']:
			ans.pop()
			ans.pop()
	print(''.join(ans[len(ans)-1:0:-1]))
T=int(input())
for i in range(T):
	solve()