#include <bits/stdc++.h>
using std::cin;
using std::cout;
using std::endl;
using std::set;
using std::map;
using std::min;
using std::max;
using std::vector;
using std::deque;
using std::queue;
using std::min;
using std::max;
using std::swap;
using std::string;
using std::sort;
using std::unique;
typedef long long ll;
typedef double db;
const int MOD = 1000000007;
const int N = 1000005;
struct Pir
{
    ll x,y;
};
ll get_gcd(ll x,ll y) {return (y==0) ? x : get_gcd(y,x%y);}
ll power(const ll & x,const ll & mi)
{
    ll s1=1LL,s2=x,m=mi;
    while (m)
    {
        if (m&1) s1=s1*s2%MOD;
        s2=s2*s2%MOD;
        m>>=1;
    }
    return s1;
}
inline ll get_inv(ll x)
{
    return power(x,MOD - 2);
}
ll dp[1005][1005][12];
void solve()
{
    int n,m;
    cin>>n>>m;
    if (dp[n][m][0]==0) puts("-1");else
    cout<<dp[n][m][0]<<endl;
    return;
}
int main()
{
    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(j,10);++k)
            {
                dp[i+1][j][0]=(dp[i+1][j][0]+dp[i][j][k])%MOD;
                dp[i+1][j+1][k+1]=(dp[i+1][j+1][k+1]+1LL*dp[i][j][k]*i%MOD)%MOD;
            }
    }
    int T=1;
    cin>>T;
    while (T--) solve();
    return 0;
}