#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>

int main() {
    
    int q,n,i;
    int flag=0;
    long int x[1000],y[1000],sum=0;
    scanf("%d",&q);
    while(q!=0)
    { scanf("%d",&n);
     
    for(i=0;i<n;i++)
    {    
    scanf("%ld%ld",&x[i],&y[i]);
        sum=x[i]+y[i];
     if((x[i]!=0&&y[i]!=0)||(x[i]<sum&&y[i]<sum))
        { printf("NO\n");
         flag=1;
         break;
        }
        
        
    } 
     if(flag==0)
     printf("YES\n");
     
     
     q--;
     
    }
    

    /* Enter your code here. Read input from STDIN. Print output to STDOUT */    
    return 0;
}