#include <bits/stdc++.h>
using namespace std;
const int M = 100005;
long long int N = 1e9 + 7;
long long int Z = 998244353;
int gcd(int a, int b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
void precompute() {}
int max3(int x, int y, int z) { return max(x, max(y, z)); }
long long int power(long long int x, unsigned int y, int p) {
  long long int res = 1;
  x = x % p;
  while (y > 0) {
    if (y & 1) res = (res * x) % p;
    y = y >> 1;
    x = (x * x) % p;
  }
  return res;
}
long long int modinv(long long int x, int p) { return (power(x, p - 2, p)); }
bool compare(const pair<int, int> &p1, const pair<int, int> &p2) {
  return (p1.first > p2.first);
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int t;
  cin >> t;
  precompute();
  while (t--) {
    int n, x = 0, y = 0, prevx = 0, prevy = 0;
    cin >> n;
    int flag = 0;
    for (int i = 0; i < n; i++) {
      cin >> x >> y;
      if (((x - prevx) >= 0) && ((y - prevy) >= 0) &&
          (y - prevy) <= (x - prevx)) {
      } else {
        flag = 1;
      }
      prevx = x;
      prevy = y;
    }
    if (flag == 1) {
      cout << "NO\n";
    } else {
      cout << "YES\n";
    }
  }
  return 0;
}
