#include <bits/stdc++.h>
#define MAXN 1000100
#define pii pair<int, int>
#define vi vector<int>
#define pb push_back
#define inf 1e18
#define F first
#define S second
#define mt make_tuple
typedef long long ll;

using namespace std;

int n, a[MAXN];

void solve(){
	cin >> n;
	for(int i = 0; i < 2 * n; i++){
		cin >> a[i];
	}
	sort(a, a+2*n);
	for(int i = 0; i < n; i++){
		cout << a[n - i - 1] << " " << a[n + i] << " ";
	}
	cout << endl;
}

int main(){
	//freopen("input.txt", "r", stdin);
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
	int T = 1;
    cin >> T;
	for(int i = 1; i <= T; i++){
		solve();
	}
}
