#include<bits/stdc++.h>
using namespace std;

int main()
{
    int testcase;
    cin>>testcase;

    for(int j=0; j<testcase; j++)
    {
        int field, flag=0, check_play, check_win;
        cin>>field;
        int play[field], win[field];
        for(int i=0; i<field; i++)
        {
            cin>>play[i]>>win[i];
        }

        if(play[0]<win[0])
        {
            flag++;
        }

        for(int i=1; i<field; i++)
        {
            if(play[i]<win[i])
            {
                flag++;
            }

            check_play=play[i]-play[i-1];
            check_win=win[i]-win[i-1];

            if(check_play<0 || check_win<0)
            {
                flag++;
            }

            if(check_play<check_win)
            {
                flag++;
            }
        }
        if(flag>0)
        {
            cout<<"NO"<<endl;
        }
        else
            cout<<"Yes"<<endl;
    }
}