#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define pb                push_back
#define ppb               pop_back
#define pf                push_front
#define ppf               pop_front
#define all(x)            (x).begin(),(x).end()
#define uniq(v)           (v).erase(unique(all(v)),(v).end())
#define sz(x)             (int)((x).size())
#define fr                first
#define sc                second



// This functions finds all primes smaller than 'limit'
// using simple sieve of eratosthenes. It also stores
// found primes in vector prime[]
vector<ll> prime;
void simpleSieve(int limit)
{
    // Create a boolean array "mark[0..n-1]" and initialize
    // all entries of it as true. A value in mark[p] will
    // finally be false if 'p' is Not a prime, else true.
    vector<bool> mark(limit + 1, true);
     prime.pb(1);
    for (int p=2; p*p<limit; p++)
    {
        // If p is not changed, then it is a prime
        if (mark[p] == true)
        {
            // Update all multiples of p
            for (int i=p*p; i<limit; i+=p)
                mark[i] = false;
        }
    }

    // Print all prime numbers and store them in prime
    for (int p=2; p<limit; p++)
    {
        if (mark[p] == true)
        {
            prime.push_back(p);
        }
    }
}

long long binpow(long long a, long long b, long long m) {
    a %= m;
    long long res = 1;
    while (b > 0) {
        if (b & 1)
            res = res * a % m;
        a = a * a % m;
        b >>= 1;
    }
    return res;
}
ll m=1e9+7;
ll MX=1e5+5;



void solve(ll t)
{
//cout<<"NEVER GIVE UP"<<endl;
ll N;
cin>>N;
vector<ll> v(2*N);
for(ll i=0;i<2*N;i++)
    cin>>v[i];
    sort(all(v));
    for(ll i=0;i<N;i++)
    {

        cout<<v[i]<<" "<<v[2*N-i-1]<<" ";
    }
    cout<<endl;
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
   ll t=1;
    cin>>t;
    //simpleSieve(1000000);
    for(ll i=1;i<=t;i++)
    {
    solve(i);
    }
    return(0);
}
