t = int(input())

def erase_ab(str):
    if "ABB" in str:
        s1 = str.replace("ABB","B",1)
        str = erase_ab(s1)
        return str
    else:
        return str


for i in range(t):
    n = int(input())
    s = input()
    print(erase_ab(s))