#include<bits/stdc++.h>
#define ls ch[x][0]
#define rs ch[x][1]
#define ll long long
#define int ll
using namespace std;

inline ll read(){
    ll num=0,neg=1;char c=getchar();
    while(!isdigit(c)){if(c=='-')neg=-1;c=getchar();}
    while(isdigit(c)){num=(num<<3)+(num<<1)+c-'0';c=getchar();}
    return num*neg;
}

const ll mod=1e9+7;
int f[1010][1010][11];
ll T,n,m,tmp;

signed main(){
    f[1][0][0]=1;
    for(int i=2;i<=1000;i++){
        for(int j=0;j<=i;j++){
            for(int k=0;k<=10;k++) f[i][j][0]=(f[i][j][0]+f[i-1][j][k])%mod;
            if(j>0) {
                for(int k=1;k<=10;k++) tmp=1ll*f[i-1][j-1][k-1]*(1ll*i-1ll)%mod,f[i][j][k]=(int)tmp;
            }
        }
    }
    T=read();
    while(T--){
        n=read(),m=read();
        if(!f[n][m][0]) printf("-1\n");
        else printf("%d\n",f[n][m][0]);
    }return 0;
}