#include<bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define rep(i, a, b) for(int i = (a); i < (b); i++)
#define per(i, a, b) for(int i = (b) - 1; i >= (a); --i)
#define de(x) cout << #x << " = " << x << endl
#define dd(x) cout << #x << " = " << x << " "
#define endl '\n'
#define pw(x) (1ll<<(x))
#define all(x) x.begin(), x.end()
#define sz(x) (int)x. size()
typedef long long ll;
typedef double db;
typedef pair<int, int> pii;
typedef vector<int> vi;

int t;
int n,m;
const int N=1000;
ll dp[N+1][N+1];
const ll mod=1e9+7;

ll cal(int st,int en)
{
    st--;
    en--;
    ll ret=1;
    rep(i,st,en+1)
    {
        ret=ret*i;
        ret%=mod;
    }
    return ret;
}


int main()
{
    std::ios::sync_with_stdio(0);
    std::cin.tie(0);

    memset(dp,0,sizeof(dp));
    dp[1][0]=1;
    rep(i,2,N+1)
    {
        rep(j,0,i)
        {
            rep(k,1,11+1)
            {
                if(i-k>=1&&j-k+1>=0)
                {
                    dp[i][j]+=dp[i-k][j-k+1]*cal(i-k+1,i-1);
                    dp[i][j]%=mod;
                }
            }
        }
    }

    while(cin>>t)
    {
        while(t--)
        {
            cin>>n>>m;
            if(dp[n][m]==0)dp[n][m]=-1;
            cout<<dp[n][m]<<endl;
        }
    }

    return 0;
}