#include <bits/stdc++.h>
using namespace std;
const long long INF = 0x7fffffffffffffff;
const int inf = 0x3f3f3f3f;
const double eps = 1e-8;
const int N = 1e5 + 5;
clock_t start, finish;
void time_in() { start = clock(); }
void time_out() {
  finish = clock();
  double tim = (double)(finish - start) / CLOCKS_PER_SEC;
  printf("Running time is %lf\n", tim);
}
inline long long mul(long long a, long long b) {
  long long s = 0;
  while (b) {
    if (b & 1) s = (s + a) % 1000000007;
    a = (a << 1) % 1000000007;
    b >>= 1;
  }
  return s % 1000000007;
}
inline long long pow_mul(long long a, long long b) {
  long long s = 1;
  while (b) {
    if (b & 1) s = mul(s, a);
    a = mul(a, a);
    b >>= 1;
  }
  return s;
}
inline long long poww(long long a, long long b) {
  long long s = 1;
  while (b) {
    if (b & 1) s = (s * a) % 1000000007;
    a = (a * a) % 1000000007;
    b >>= 1;
  }
  return s % 1000000007;
}
inline int read() {
  char c = getchar();
  int sgn = 1, ret = 0;
  while (c != '-' && (c < '0' || c > '9')) c = getchar();
  if (c == '-') sgn = -1, c = getchar();
  while (c >= '0' && c <= '9') ret = ret * 10 + c - 48, c = getchar();
  return ret * sgn;
}
void write(int x) {
  if (x > 9) write(x / 10);
  putchar(x % 10 + '0');
}
inline long long phi(long long x) {
  long long ans = x;
  for (long long i = 2; i * i <= x; i++)
    if (x % i == 0) {
      ans -= ans / i;
      while (x % i == 0) x /= i;
    }
  if (x > 1) ans -= ans / x;
  return ans;
}
long long inv(long long down) {
  return down == 1
             ? 1
             : ((1000000007 - 1000000007 / down) * inv(1000000007 % down)) %
                   1000000007;
}
int a[105] = {0}, b[105] = {0};
int main() {
  int T;
  scanf("%d", &T);
  while (T--) {
    int n, f = 0;
    scanf("%d", &n);
    for (int i = 1; i <= n; i++) {
      scanf("%d %d", &a[i], &b[i]);
      if (a[i] < a[i - 1] || b[i] < b[i - 1]) f = 1;
      if (b[i] - b[i - 1] > a[i] - a[i - 1]) f = 1;
    }
    if (f)
      printf("NO\n");
    else
      printf("YES\n");
  }
}
