#include <bits/stdc++.h>
using namespace std;
const long long MOD = 1e9 + 7;
const long long INF = 1e18;
const long long MAX = 100100;
void pre() {}
void solve() {
  long long n;
  cin >> n;
  vector<long long> p(n), c(n);
  for (long long i = 0; i < n; ++i) cin >> p[i] >> c[i];
  for (long long i = 0; i < n; ++i) {
    if (c[i] > p[i]) {
      cout << "NO"
           << "\n";
      return;
    }
  }
  for (long long i = 1; i < n; ++i) {
    if (p[i] < p[i - 1]) {
      cout << "NO"
           << "\n";
      return;
    }
    if (c[i] < c[i - 1]) {
      cout << "NO"
           << "\n";
      return;
    }
    if ((p[i] - p[i - 1]) < (c[i] - c[i - 1])) {
      cout << "NO"
           << "\n";
      return;
    }
  }
  cout << "YES"
       << "\n";
}
signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  pre();
  long long t = 1;
  cin >> t;
  for (long long CASE = 1; CASE <= t; ++CASE) {
    solve();
  }
  {};
  return 0;
}
