#include <bits/stdc++.h>
using namespace std;
const double pi = acos(-1.0);
const double eps = 1e-11;
template <class T>
inline void checkmin(T &a, T b) {
  if (b < a) a = b;
}
template <class T>
inline void checkmax(T &a, T b) {
  if (b > a) a = b;
}
template <class T>
inline T sqr(T x) {
  return x * x;
}
template <class T>
inline void bin(T n, int pos) {
  T i, one = 1, two = 2;
  for (i = (one << (pos - 1)); i > 0; i = (i >> 1))
    cout << ((n & i) ? "1" : "0");
  cout << endl;
}
int lsb(unsigned int v) {
  int r;
  static const int MultiplyDeBruijnBitPosition[32] = {
      0,  1,  28, 2,  29, 14, 24, 3, 30, 22, 20, 15, 25, 17, 4,  8,
      31, 27, 13, 23, 21, 19, 16, 7, 26, 12, 18, 6,  11, 5,  10, 9};
  r = MultiplyDeBruijnBitPosition[((uint32_t)((v & -v) * 0x077CB531U)) >> 27];
  return r + 1;
}
template <class T>
inline int msb(T n) {
  return (n == 0) ? 0 : (1 + msb(n >> 1));
}
template <class T>
inline T getbit(T n, int pos) {
  return ((n & (1 << pos)) ? 1 : 0);
}
template <class T>
inline int countbit(T n) {
  return (n == 0) ? 0 : (1 + countbit(n & (n - 1)));
}
template <class T>
inline void setbit(T &n, int p) {
  n = n | (1LL << p);
}
template <class T>
inline T gcd(T a, T b) {
  if (a < 0) return gcd(-a, b);
  if (b < 0) return gcd(a, -b);
  return (b == 0) ? a : gcd(b, a % b);
}
bool isequal(vector<int> a, vector<int> b) {
  for (int i = 0; i < (a.size()); i++)
    if (a[i] != b[i]) return false;
  return true;
}
template <class T>
bool allequal(vector<T> a) {
  sort(a.begin(), a.end());
  return a[0] == a[a.size() - 1];
}
template <class T>
void printarray(vector<T> a) {
  for (int i = 0; i < (a.size()); i++) cout << a[i] << " ";
  cout << endl;
}
void printmatrix(vector<vector<int>> a, int n, int m) {
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      cout << setw(4) << a[i][j];
    }
    cout << endl;
  }
}
void readmatrix(vector<vector<int>> &a, int n, int m) {
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      cin >> a[i][j];
    }
  }
}
template <class T>
void printsubarray(vector<T> a, int start, int end) {
  if (start < 0 or end > a.size() - 1) cout << "Out of bounds" << endl;
  for (int i = start; i <= end; i++) cout << a[i] << " ";
  cout << endl;
}
bool isprime(int n) {
  if (n < 2) return false;
  if (n == 2) return true;
  for (int i = 2; i * i <= n; i++) {
    if (n % i == 0) return false;
  }
  return true;
}
void split(const string &s, char c, vector<string> &result) {
  stringstream ss(s);
  string x;
  while (getline(ss, x, c)) result.push_back(x);
}
void err(vector<string>::iterator it) {}
template <typename T, typename... Args>
void err(vector<string>::iterator it, T a, Args... args) {
  cerr << it->substr((*it)[0] == ' ', it->length()) << " = " << a << '\n';
  err(++it, args...);
}
void yup() { cout << "Yes" << endl; }
void nope() { cout << "No" << endl; }
void Yup() { cout << "YES" << endl; }
void Nope() { cout << "NO" << endl; }
void readarray(vector<int> &a, int size) {
  int tmp;
  a.clear();
  for (int i = 0; i < (size); i++) {
    cin >> tmp;
    a.push_back(tmp);
  }
}
void solvecase() {
  int n, m;
  int k;
  cin >> n;
  pair<int, int> g[111];
  for (int i = 0; i < n; i++) {
    cin >> g[i].first >> g[i].second;
  }
  bool ok = true;
  if (g[0].first < g[0].second) ok = false;
  for (int i = 1; i < n; i++) {
    if ((g[i].first < g[i - 1].first) or (g[i].second < g[i - 1].second))
      ok = false;
  }
  for (int i = 1; i < n; i++) {
    int jumpc = g[i].second - g[i - 1].second;
    int jumpp = g[i].first - g[i - 1].first;
    if (jumpc > jumpp) ok = false;
  }
  ok ? Yup() : Nope();
}
int main() {
  int cases = 1;
  cin >> cases;
  while (cases--) {
    solvecase();
  }
  return 0;
}
