#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
void input(long long int n, long long int a[]) {
  for (long long int i = 0; i < n; ++i) cin >> a[i];
}
long long int bin_expo(long long int A, long long int B, long long int M) {
  long long int result = 1ll;
  while (B > 0) {
    if (B % 2 == 1) {
      result = (result * A) % M;
    }
    A = (A * A) % M;
    B = B / 2;
  }
  return result;
}
long long int gcd(long long int a, long long int b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long int lcm(long long int a, long long int b) {
  return (a * b) / gcd(a, b);
}
int main() {
  ios_base::sync_with_stdio(0);
  long long int t;
  cin >> t;
  while (t--) {
    long long int n;
    cin >> n;
    pair<long long int, long long int> pa[n];
    for (long long int i = 0; i < n; ++i) cin >> pa[i].first >> pa[i].second;
    long long int flag = 0;
    for (long long int i = 0; i < n; ++i) {
      if (pa[i].first < pa[i].second) {
        flag = 1;
        break;
      }
    }
    for (int i = 1; i < n; i++) {
      long long int tot_plays = pa[i].first - pa[i - 1].first;
      long long int tot_score = pa[i].second - pa[i - 1].second;
      if (tot_plays >= 0 && tot_score >= 0 && tot_score <= tot_plays) continue;
      flag = 1;
      break;
    }
    if (flag)
      cout << "NO" << endl;
    else
      cout << "YES" << endl;
  }
  return 0;
}
