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


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */  
    int Q;
    cin>>Q;
    for(int q=1;q<=Q;q++)
        {
        int n;
        cin>>n;
        int a[n][2];
        for(int i=0;i<n;i++)
            cin>>a[i][0]>>a[i][1];
        for(int i=0;i<n;i++)
            {
            if(a[i][0]==0||a[i][1]==0)
                continue;
            else
                {
                cout<<"NO\n";
                goto here;
            }
        }
        cout<<"YES\n";
        here:;
    }
    return 0;
}