#include <bits/stdc++.h>
using namespace std;
inline int qpow(int b, long long e, int m = 998244353) {
  int a = 1;
  for (; e; e >>= 1, b = (long long)b * b % m)
    if (e & 1) a = (long long)a * b % m;
  return a;
}
int n, m, q, k;
int a[300005], b[300005];
int main() {
  int tests = 1;
  scanf("%d", &tests);
  while (tests--) {
    scanf("%d", &n);
    for (int i = 1; i <= (n); ++i) scanf("%d%d", a + i, b + i);
    int ok = 1;
    for (int i = 1; i <= (n); ++i)
      if (a[i] < a[i - 1] || b[i] < b[i - 1]) ok = 0;
    for (int i = 1; i <= (n); ++i)
      if (a[i] - a[i - 1] < b[i] - b[i - 1]) ok = 0;
    puts(ok ? "YES" : "NO");
  }
  return 0;
}
