#pragma GCC optimize("Ofast")
#include<bits/stdc++.h>
using namespace std;
#define ll long long int

void solve(){
	ll n; cin >> n;
	vector<ll> a(2*n);
	ll i, j;
	for(i = 0; i < 2*n; i++) cin >> a[i];
	sort(a.begin(), a.end());
	for(i = 0; i < n; i++)
		cout << a[i] << " " << a[2*n -i - 1] << " ";
	cout << "\n";
}
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int T; cin >> T;
    while(T--) solve();
}
