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

#define Int register int
#define mod 1000000007
#define MAXN 1005

template <typename T> inline void read (T &t){t = 0;char c = getchar();int f = 1;while (c < '0' || c > '9'){if (c == '-') f = -f;c = getchar();}while (c >= '0' && c <= '9'){t = (t << 3) + (t << 1) + c - '0';c = getchar();} t *= f;}
template <typename T,typename ... Args> inline void read (T &t,Args&... args){read (t);read (args...);}
template <typename T> inline void write (T x){if (x < 0){x = -x;putchar ('-');}if (x > 9) write (x / 10);putchar (x % 10 + '0');}

int t,n,m,dp[MAXN][MAXN][11];

signed main(){
    read (t);
    while (t --){
        read (n,m);
        memset (dp,0,sizeof (dp));
        for (Int i = 0;i <= n;++ i) dp[i][0][0] = 1;
        for (Int i = 1;i <= n;++ i){
            for (Int j = 1;j <= m && j <= i;++ j){
                for (Int k = 1;k <= 10;++ k) dp[i][j][k] = 1ll * dp[i - 1][j - 1][k - 1] * (i - 1) % mod;
                for (Int k = 0;k <= 10;++ k) dp[i][j][0] = (dp[i][j][0] + dp[i - 1][j][k]) % mod;
            }
        }
        if (!dp[n][m][0]){
            puts ("-1");
            continue;
        }
        write (dp[n][m][0]),putchar ('\n');
    }
    return 0;
}