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

int main() {
  int t; 
  cin >>t; 
  while (t>0){  
    t--; 
    int n; 
    cin >> n; 
    int nos[2*n]; 
    for(int i =0;i<(2*n);i++){
      cin >> nos[i]; 
    }
    sort(nos,nos+2*n); 
    for (int i =0;i<n;i++){
      cout << nos[i] << " " << nos[2*n - i - 1] << " "; 
    }
    cout << "\n";
  }
}