import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################
t = ni()
for _ in range(t):
    n = ni()
    s = input()
    p = []
    for i in range(n):
        p.append(s[i])
        while len(p)>=3 and p[-3:] == ["A","B","B"]:
            p.pop()
            p.pop()
            p.pop()
            p.append("B")
        #print(p)
    print("".join(p))