#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    int q;
    cin>>q;
    int i;
    for(i=0;i<q;i++){
        int n,j,d=0;
        cin>>n;
        long int x,y;
        for(j=0;j<n;j++){
            cin>>x>>y;
            if(x!=0 && y!=0){
                d=1;
            }
        }
        if(d==1){
            cout<<"NO";
        }
        else{
            cout<<"YES";
        }
        if(i!=q-1){
            cout<<endl;
        }
    }
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}