1334A

#include <stdio.h>
#include <string.h>
#include <vector>
#include <algorithm>
#include <assert.h>
#include <stdlib.h>
using namespace std;


struct peek {
    int plays, clears;
};

int main(){
    int T;
    scanf("%d", &T);
    while (T--){
        int n;
        scanf("%d",&n);
        vector<peek> peeks(n);
        //Cargar valores
        for (int i=0; i<n; i++){
            peek aux;
            scanf("%d %d", &(aux.plays), &(aux.clears));
            peeks[i] = aux;
        }
        //Analizar
        int invalido = 0;
        if (peeks[0].plays < peeks[0].clears) invalido++;
        for (int i=1; i<n && !invalido; i++){
            if (peeks[i].plays < peeks[i].clears){
                invalido++;
            }
            if (peeks[i-1].plays>peeks[i].plays){
                //Disminuyó
                invalido++;
            }
            if (peeks[i-1].clears>peeks[i].clears){
               //Disminuyó
                invalido++;
            }
            if (peeks[i].clears-peeks[i-1].clears > peeks[i].plays - peeks[i-1].plays){
                // Clear aumento mas rapido que plays, no puede pasar
                invalido++;
            }
        }
        printf("%s\n", invalido ? "NO" : "YES");
    }
    return 0;
}