import java.io.*;
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        StringBuilder sb = new StringBuilder();
        ArrayDeque<Character> deq = new ArrayDeque<>();
        while (n-- > 0) {
            int x = sc.nextInt();
            char[] arr = sc.next().toCharArray();
            for (int i = x - 1; i >= 0; i--) {
                if (arr[i] == 'A' && deq.size() >= 2) { 
                    char p = deq.pop();
                    if (p == 'B' && deq.peek() == 'B') {
                        
                    } else {
                        deq.push('B');
                        deq.push('A');
                    }
                } else {
                    deq.push(arr[i]);
                }
            }
            while (deq.size() > 0) {
                sb.append(deq.pop());
            }
            sb.append("\n");
        }
        System.out.print(sb);
    }
}
    
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
    
}