def solve(n,s):
    ans=[]
    for i in range(n):
        if ans:
            if ans[-1]=='A' and s[i]=='B':
                if i+1<n and s[i+1]=='B':
                    ans.pop()
                    while len(ans)>=2 and ans[-2]=='A' and ans[-1]=='B':
                        ans.pop()
                        ans.pop()
                else:
                    ans.append(s[i])
            else:
                ans.append(s[i])
        else:
            ans.append(s[i])
    print(*ans,sep='')
t=int(input())
for _ in range(t):
    n=int(input())
    s=input()
    solve(n,s)