#include <bits/stdc++.h>
using namespace std;
void solve() {
  long long int n, i, j, ca, pa, sign = 0;
  cin >> n;
  long long int C[n + 1], P[n + 1];
  C[0] = 0, P[0] = 0;
  for (i = 1; i <= n; i++) {
    cin >> P[i] >> C[i];
    if (C[i] < C[i - 1] || P[i] < P[i - 1]) {
      sign = 1;
    }
    if (P[i] < C[i]) sign = 1;
  }
  for (i = 1; i <= n; i++) {
    if ((P[i] - P[i - 1]) < (C[i] - C[i - 1])) sign = 1;
  }
  if (sign == 1)
    cout << "NO" << endl;
  else
    cout << "YES" << endl;
}
void fast() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
}
int main() {
  fast();
  int t = 1;
  cin >> t;
  while (t--) {
    solve();
  }
  return 0;
}
