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 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(); } }