#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <cmath>
#include <set>
#include <vector>
#include <utility>
#include <stack>
#include <deque>
#include <queue>
#include <string>
#include <cctype>
#include <ctime>
#include <sstream>
#include <map>
//#define LOCAL
#define ll long long
#define maxn 100010
#define maxm 1005
#define mod 1000000007
using namespace std;

int n, m;
ll d[maxm][11][2];   // 访问到第i个位置，已经使用了j个传送器，尾端连续k个

ll fn(int u)
{
    if(u == 0) return 1;
    else return((u*fn(u-1)) % mod);
}

int main()
{
#ifdef LOCAL
    freopen("data.in.txt", "r", stdin);
    freopen("data.out.txt", "w", stdout);
#endif
    int t; cin >> t;
    while(t--)
    {
        scanf("%d%d", &n, &m);
        memset(d, 0, sizeof(d));

        int p = 0;
        d[0][0][1] = 1;
        for(int i = 2; i <= n-1; i++)
        {
            for(int j = 0; j <= m; j++)
                for(int k = 0; k <= 10; k++)
                    d[j][k][p] = 0;
            for(int j = min(m, i-1); j >= 0; j--)
            {
                for(int k = min(10, j); k >= 1; k--)
                    d[j][k][p] = (d[j-1][k-1][p^1] * (i-1)) % mod;
                for(int k = min(10, j); k >= 0; k--)
                    d[j][0][p] = (d[j][0][p] + d[j][k][p^1]) % mod;
            }
            p ^= 1;
        }
        ll ans = 0; int ok = 0;
        for(int k = 0; k <= 10; k++)
        {
            if(d[m][k][p^1] != 0) ok = 1;
            ans = (ans + d[m][k][p^1]) % mod;
        }
        if(ok == 0) printf("-1\n");
        else printf("%lld\n", ans);
    }
    return 0;
}