#include <bits/stdc++.h>
using namespace std;
void solve() {
  long long n;
  cin >> n;
  pair<long long, long long> a[n];
  for (long long i = 0; i < n; ++i) {
    cin >> a[i].first >> a[i].second;
  }
  if (a[0].first < a[0].second) {
    cout << "NO" << '\n';
    return;
  }
  for (long long i = 1; i < n; ++i) {
    if (a[i].first - a[i - 1].first < a[i].second - a[i - 1].second ||
        a[i].first < a[i - 1].first || a[i].second < a[i - 1].second) {
      cout << "NO" << '\n';
      return;
    }
  }
  cout << "YES" << '\n';
}
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long T = 1;
  cin >> T;
  for (long long i = 1; i <= T; ++i) {
    solve();
  }
  return 0;
}
