#include <bits/stdc++.h>
using namespace std;
const int N = 1001;
const int p = 1E9 + 7;
int f[1002][1002][13];
void init(int n) {
    f[1][0][0] = 1;
    for (int i = 0; i <= n; i++)
        for (int j = 0; j <= i; j++) {
            for (int k = 0; k <= 10; k++) {
                if (k != 10) (f[i + 1][j + 1][k + 1] += 1LL * f[i][j][k] * i % p) %= p;
                (f[i + 1][j][0] += f[i][j][k]) %= p;
            }
        }
}
void solve() {
    int n, m;
    cin >> n >> m;
    cout << (f[n][m][0] ? f[n][m][0] : -1) << endl;
}
int main() {
    init(1000);
    int T;
    cin >> T;
    while (T--) {
        solve();
    }
    return 0;
}