T=int(input())
Ans=[""]*T

for t in range(T):
    N=int(input())
    S=input()

    Q=[]
    for x in S:
        Q.append(x)
        while True:
            if len(Q)>=3 and Q[-3]=="A" and Q[-2]=="B" and Q[-1]=="B":
                Q.pop()
                Q.pop()
                Q.pop()
                Q.append("B")
            else:
                break
    Ans[t]="".join(Q)

print(*Ans,sep="\n")