T=int(input())
for _ in range(T):
    n=int(input())
    s=list(input())
    s.reverse()
    ans=[]
    for x in s:
        ans.append(x)
        if len(ans)>=3 and ans[-1]=="A" and ans[-2]=="B" and ans[-3]=="B":
            ans.pop()
            ans.pop()
    ans.reverse()
    print("".join(ans))