#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int mod = 1e9 + 9, inf = 1e9;
int n, m, fmn[100005][2], fmx[100005][2], b[100005];
char a[100005];
string Solver() {
	for (int i = 1; i <= n; i++) b[i] = a[i] - '0';
	fmn[n][b[n]] = 0;
	fmx[n][b[n]] = 0;
	fmn[n][1 - b[n]] = inf;
	fmx[n][1 - b[n]] = -inf;
	for (int i = n - 1; i >= 1; i--) {
		for (int j = 0; j < 2; j++) {
			fmn[i][j] = inf;
			fmx[i][j] = -inf;
			if (b[i] != j && a[i] != '?') continue;
			for (int k = 0; k < 2; k++) {
				fmn[i][j] = min(fmn[i][j], fmn[i + 1][k] + (j != k));
				fmx[i][j] = max(fmx[i][j], fmx[i + 1][k] + (j != k));
			}
		}
	}
	int u = m;
	string str;
	str.resize(n);
	for (int i = 1; i <= n; i++) {
		bool ok = 0;
		for (int j = 0; j < 2; j++) {
			int nu = u;
			if (i > 1) nu -= (j != str[i - 2] - '0');
			if (fmn[i][j] <= nu && nu <= fmx[i][j] && fmn[i][j] % 2 == nu % 2) {
				str[i - 1] = j + '0';
				ok = 1;
				u = nu;
				break;
			}
		}
		if (!ok) {
			str.resize(n + 5);
			fill(str.begin(), str.end(), '2');
			return str;
		}
	}
	return str;
}
void Solve() {
	scanf("%d%d%s", &n, &m, a + 1);
	string ans;
	if (a[n] == '?') {
		a[n] = '1', ans = Solver();
		a[n] = '0', ans = min(ans, Solver());
	} else ans = Solver();
	if (ans.length() > n) cout << "Impossible\n";
	else cout << ans << '\n';
}
int main() {
	int t;
	scanf("%d", &t);
	while (t--) Solve();
}