#include <bits/stdc++.h>

#include <atcoder/all>
#define rep(i, n) for (int i = 0; i < (n); i++)
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef pair<int, int> P;
template <typename T>
using min_priority_queue = priority_queue<T, vector<T>, greater<T>>;
const double PI = 3.14159265358979323846;
int ddx[] = {1, -1, 0, 0, 1, 1, -1, -1};
int ddy[] = {0, 0, 1, -1, 1, -1, 1, -1};
int dx[] = {1, 0, -1, 0};
int dy[] = {0, 1, 0, -1};

void cans(bool f) {
    if (f)
        cout << "Yes" << endl;
    else
        cout << "No" << endl;
}

template <typename T>
T gcd(T a, T b) {
    if (b == 0)
        return a;
    else
        return gcd(b, a % b);
}

bool compare1(pair<ll, ll> a, pair<ll, ll> b) { return a.first < b.first; }
bool compare2(pair<ll, ll> a, pair<ll, ll> b) { return a.second < b.second; }

ll m = 998244353;

long long modpow(long long a, long long n, long long mod = 998244353) {
    long long res = 1;
    while (n > 0) {
        if (n & 1) res = res * a % mod;
        a = a * a % mod;
        n >>= 1;
    }
    return res;
}

template <typename T>
bool chmax(T& a, const T& b) {
    if (a < b) {
        a = b;  // aをbで更新
        return true;
    }
    return false;
}
template <typename T>
bool chmin(T& a, const T& b) {
    if (a > b) {
        a = b;  // aをbで更新
        return true;
    }
    return false;
}

int main() {
    int T;
    cin >> T;
    rep(i, T) {
        int N;
        cin >> N;
        string S;
        cin >> S;
        stack<char> st;
        rep(i, N) {
            if (st.empty()) {
                st.push(S.back());
                S.pop_back();
                continue;
            }
            char c = st.top();
            st.pop();
            if (st.empty()) {
                st.push(c);
                st.push(S.back());
                S.pop_back();
                continue;
            }
            if (st.top() == 'B' && c == 'B' && S.back() == 'A') {
                S.pop_back();
                continue;
            } else {
                st.push(c);
                st.push(S.back());
                S.pop_back();
            }
        }
        string ans = "";
        while (!st.empty()) {
            ans = ans + st.top();
            st.pop();
        }
        cout << ans << endl;
    }
}