#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long t;
  cin >> t;
  while (t--) {
    long long n, flag = 1;
    cin >> n;
    long long p[n + 1], c[n + 1];
    long long diff1 = 0, diff2 = 0;
    for (long long i = 1; i <= n; i++) {
      cin >> p[i] >> c[i];
    }
    for (long long i = 1; i <= n; i++) {
      diff1 = p[i] - diff1;
      diff2 = c[i] - diff2;
      if (diff1 < diff2 || diff1 < 0 || diff2 < 0) {
        flag = 0;
        break;
      }
      diff1 = p[i];
      diff2 = c[i];
    }
    if (flag == 1)
      cout << "YES" << endl;
    else
      cout << "NO" << endl;
  }
  return 0;
}
