//BISMILLAH
#include<bits/stdc++.h>
#define ll long long int
#define gcd(a,b) __gcd(a,b)
#define mod 1000000007
#define ss second
#define ff first
using namespace std;
int main()
{
   ll tc;
   cin>>tc;
   while(tc--)
   {
       ll n;
       cin>>n;
       ll a[(2*n)+1],i;
       for(i=0;i<2*n;i++)
       {
           cin>>a[i];
       }
       sort(a,a+(2*n));
       ll j=(2*n)-1;
       for(i=0;i<n;i++)
       {
           cout<<a[j]<<" "<<a[i]<<" ";
           j--;
       }
       cout<<endl;
   }
}
