/* -*- coding: utf-8 -*-
 *
 * 1894.cc:  No.1894 Delete AB - yukicoder
 */

#include<cstdio>
#include<string>
#include<algorithm>
 
using namespace std;

/* constant */

const int MAX_N = 200000;

/* typedef */

/* global variables */

char s[MAX_N + 4];

/* subroutines */

/* main */

int main() {
  int tn;
  scanf("%d", &tn);

  while (tn--) {
    int n;
    scanf("%d%s", &n, s);

    string t;
    for (int i = 0; i < n; i++) {
      if (s[i] == 'A')
	t.push_back('A');
      else {
	while (! t.empty() && t.back() == '-') t.pop_back();
	if (! t.empty() && t.back() == 'A') t.back() = '-';
	else t.push_back('B');
      }
    }

    for (auto c: t) {
      if (c == '-') putchar('A'), putchar('B');
      else putchar(c);
    }
    putchar('\n');
  }
  return 0;
}