#include<bits/stdc++.h>
using namespace std;
void solve(){
    string S;
    int N;
    cin>>N>>S;
    stack<char> C;
    for(int i=N-1;i>=0;i--){
        if(C.size()<2||S[i]=='B')C.push(S[i]);
        else if(C.top()=='B'){
            C.pop();
            if(C.top()!='B'){
                C.push('B');
                C.push('A');
            }
        }
    }
    while(!C.empty()){
        cout<<C.top();
        C.pop();
    }
    cout<<endl;
    return;
}
int main() {
    int T;
    cin>>T;
    while(T--)solve();
}