#include <stdio.h>

void solve(int N, char S[])
{
	int i, k = 0;
	static int s[200001];
	for (i = N - 1; i >= 0; i--) {
		if (k <= 1) s[k++] = i;
		else if (S[i] == 'A' && S[s[k-1]] == 'B' && S[s[k-2]] == 'B') k--;
		else s[k++] = i;
	}
	while (k > 0) printf("%c", S[s[--k]]);
	printf("\n");
}

int main()
{
	int t, T, N;
	char S[200001];
	scanf("%d", &T);
	for (t = 1; t <= T; t++) {
		scanf("%d", &N);
		scanf("%s", S);
		solve(N, S);
	}
	fflush(stdout);
	return 0;
}