#include<bits/stdc++.h>
# define ll long long int
using namespace std;
int main()
{
  ll t;
  cin>>t;
  while(t--)
  {
    ll n;
    cin>>n;
ll arr[2*n];
for(ll i=0;i<2*n;i++)
cin>>arr[i];
sort(arr,arr+2*n);
ll m=0,a=2*n-1;
while(true)
{
  cout<<arr[m]<<" "<<arr[a]<<" ";
  m++;
  a--;
  if(m==n)
  break;
}
cout<<endl;
  }
}
