#include <bits/stdc++.h>
using namespace std;

const int MOD = 1e9+7;
void add(int &a, int b) {
    a += b;
    if (a >= MOD) a -=MOD;
}

int dp[1010][1010][11];

int main() {

    memset(dp, 0, sizeof(dp));
    dp[0][0][0] = 1;
    for (int i = 0; i <= 1000; i++)
        for (int j = 0; j <= i; j++) 
            for (int k = 0; k <= min(10, j); k++) {
                if (dp[i][j][k] == 0) continue;
                add(dp[i+1][j][0], dp[i][j][k]);
                if (k < 10) {
                    add(dp[i+1][j+1][k+1], (long long)dp[i][j][k]*i%MOD);
                }
            }

    int T;
    scanf("%d", &T);
    while (T--) {
        int n, m;
        scanf("%d%d", &n, &m);
        printf("%d\n", dp[n][m][0] == 0 ? -1 : dp[n][m][0]);
    }
    return 0;
}