#include <bits/stdc++.h>
const int N = 1e5 + 5;
const int INF = 0x3f3f3f3f;
const int MAXINT = 2147483647;
const int mod = 1000000007;
const long long MAXLONG = 9223372036854775807;
using namespace std;
template <class T>
inline bool Read(T &ret) {
  char c;
  int sgn;
  if (static_cast<void>(c = getchar()), c == EOF) return 0;
  while (c != '-' && (c < '0' || c > '9')) c = getchar();
  sgn = (c == '-') ? -1 : 1;
  ret = (c == '-') ? 0 : (c - '0');
  while (static_cast<void>(c = getchar()), c >= '0' && c <= '9')
    ret = ret * 10 + (c - '0');
  ret *= sgn;
  return 1;
}
template <class T>
inline void Write(T x) {
  if (x < 0) putchar('-'), Write(x);
  if (x > 9) Write(x / 10);
  putchar(x % 10 + '0');
}
void solve(int question_num) {
  while (question_num--) {
    int n;
    cin >> n;
    struct node {
      int a, b;
      node() : a(0), b(0) {}
    } a[103];
    for (int i = 1; i <= n; ++i) {
      cin >> a[i].a >> a[i].b;
    }
    int flage = 0;
    for (int i = 1; i <= n; ++i) {
      if ((a[i].a < a[i - 1].a) || (a[i].b < a[i - 1].b)) {
        flage = 1;
        break;
      }
      if (a[i].a - a[i - 1].a >= a[i].b - a[i - 1].b) continue;
      flage = 1;
      break;
    }
    if (flage)
      cout << "NO\n";
    else
      cout << "YES\n";
  }
}
int main() {
  int t = 1;
  cin >> t;
  solve(t);
  return 0;
}
