#include <bits/stdc++.h>
#define ll long long
#define mod 1000000007
using namespace std;


int main(){
	int t;
	cin >>t;
	while(t--){
	int n;
        cin >> n;
        int arr[2*n];
        for(int i=0;i<2*n;i++)cin >> arr[i];
        

        sort(arr, arr+2*n);
        for(int i=0;i<n;i++) {
                cout << arr[i] << " " << arr[2*n-i-1] << " ";
        }
        cout << '\n';
    }
}


