#include <bits/stdc++.h>
#include <atcoder/modint>
using namespace std;
using namespace atcoder;
using ll = long long;
using mint =  modint1000000007;
#define rep(i,n) for (int i = 0; i < n; i++)
#define rrep(i,n) for (int i = n-1; i >= 0; i--)
#define rep2(i,a,b) for (int i = a; i < b; i++)
#define rrep2(i,a,b) for (int i = a-1; i >= b; i--)
#define rep3(i,a,b,c) for (int i = a; i < b; i+=c)
#define rrep3(i,a,b,c) for (int i = a-1; i >= b; i-=c)
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
template<class T> bool chmax(T &a, T b){if (a < b){a = b;return true;} else return false;}
template<class T> bool chmin(T &a, T b){if (a > b){a = b;return true;} else return false;}
template<class T> T power(T x, ll y){if (y == 0) return 1;T p = pow(x,y/2);if (y%2 == 0) return p*p;else return p*p*x;}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int t; cin >> t;
    while (t--){
        int n; cin >> n;
        string s,t = ""; cin >> s;
        deque<char> dq;
        dq.push_front(s[n-1]);
        rrep(i,n-1){
            if (dq.empty()) dq.push_front(s[i]);
            else{
                if (s[i] == 'A' && dq.front() == 'B'){
                    if (dq.size() == 1) dq.push_front('A');
                    else{
                        if (dq[1] == 'A') dq.push_front('A');
                        else dq.pop_front();
                    }
                }
                else{
                    dq.push_front(s[i]);
                }
            }
        }
        while (dq.size()){
            cout << dq.front(); dq.pop_front();
        }
        cout << endl;
    }
}