1079.cpp

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll MOD = 1e9 + 7;
const int N = 1e6 + 6;

ll fact[N], ifact[N];

ll powmod(ll a, ll b) {
  ll res = 1;
  for (; b; b >>= 1, (a *= a) %= MOD) {
    if (b & 1) {
      (res *= a) %= MOD;
    }
  }
  return res;
}

int main() {
  ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
  fact[0] = 1;
  for (int i = 1; i < N; ++i) {
    fact[i] = (fact[i - 1] * i) % MOD;
  }
  ifact[N - 1] = powmod(fact[N - 1], MOD - 2);
  for (int i = N - 1; i >= 1; --i) {
    ifact[i - 1] = (ifact[i] * i) % MOD;
  }
  int T; cin >> T;
  while (T--) {
    int n, k; cin >> n >> k;
    cout << ((((fact[n] * ifact[k]) % MOD) * ifact[n - k]) % MOD) << "\n";
  }
  return 0;
}