#include <bits/stdc++.h>
#include <atcoder/all>
#define rep(i,a,b) for(int i=a;i<b;i++)
#define rrep(i,b) for(int i=b-1;i>=0;i--)
#define rbit(i,a) for(int i=0;i<(1<<a);i++)
#define all(x) (x).begin(),(x).end()
#define pb(x) push_back(x);
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a = b; return 1; } return 0; }
typedef long long ll;
typedef long double lld;
using namespace std;
using namespace atcoder;
using mint=static_modint<1000000007>;
const ll mod=998244353;
//const ll mod=1e9+7;
int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};
const string zton="0123456789";
const string atoz="abcdefghijklmnopqrstuvwxyz";
const ll inf=(1ll<<60);
ll gcd(ll a,ll b){
    ll r;
    r=a%b;
    if(r==0){
        return b;
    }
    else{
        return gcd(b,r);
    }
}
typedef pair<ll,int> P;

void solve(){
    int N;cin >> N;
    string S;cin >> S;
    deque<char> que;
    rrep(i,N){
        if(S.at(i)=='B')que.push_front('B');
        else if(S.at(i)=='A'){
            if(que.size()<2){
                que.push_front('A');
            }
            else{
                if(que.at(0)=='B'&&que.at(1)=='B'){
                    que.pop_front();
                }
                else{
                    que.push_front('A');
                }
            }
        }
    }
    for(char c:que)cout << c ;
    cout << endl;
}

int main(void){
    int t;cin >> t;
    rep(_,0,t)solve();
}