#include"bits/stdc++.h"
using namespace std;
#define int long long
#define fio ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0)
#define endl '\n'
#define mod 1000000007
int power(int n, int k) {
    if (k == 0) {
        return 1;
    }
    int curr = power(n, k / 2);
    if (k % 2 == 0) {
        return ((curr % mod * curr % mod) % mod);
    }
    else {
        return ((n % mod * curr % mod * curr % mod) % mod);
    }
}
int min(int a, int b) {
    if (a < b)
        return a;
    else
        return b;
}
bool compare(int a, int b) {
    return a > b;
}

int32_t main() {
    fio;
    int t;
    cin >> t;
    while (t--) {
        int n;
        cin >> n;
        vector<int>v;
        for (int i = 0; i < 2 * n; i++) {
            int x;
            cin >> x;
            v.push_back(x);
        }
        vector<int>a, b;
        sort(v.begin(), v.end());
        for (int i = 0; i < n; i++) {
            a.push_back(v[i]);
        }
        reverse(a.begin(), a.end());
        for (int i = n; i < 2 * n; i++) {
            b.push_back(v[i]);
        }
        reverse(b.begin(), b.end());
        int idx_1 = 0, idx_2 = 0;
        vector<int>ans;
        for (int i = 0; i < 2 * n; i++) {
            if (i % 2 == 0) {
                ans.push_back(b[idx_2]);
                idx_2++;
            }
            else {
                ans.push_back(a[idx_1]);
                idx_1++;
            }
        }
        for (auto p : ans) {
            cout << p << " ";
        }
        cout << endl;
    }
    return 0;
}