t=int(input())
ns=[]
for _ in range(t):
    n=int(input())
    s=input()
    ns.append([n,s])
for n,s in ns:
    # Bの前にあるABは全て消す
    if n<=2:
        print(s)
        continue
    ans=[]
    s=list(s)
    i=0
    ans.append(s.pop())
    ans.append(s.pop())
    while s:
        if len(ans)>=2 and ans[-1]=="B" and ans[-2]=="B" and s[-1]=="A":
            s.pop()
            ans.pop()
        else:
            ans.append(s.pop())
    ans.reverse()
    print("".join(ans))