#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>

using namespace std;

const int N=55;

int a[N];
int t,n;

int main()
{
	cin>>t;
	while(t--)
	{
		memset(a,0,sizeof a);
		cin>>n;
		int i;
		n=n*2;
		for(i=1;i<=n;i++)
		cin>>a[i];
		sort(a+1,a+n+1);
		if(n%2!=0)
		{
		for(i=2;i<=n;i+=2)
		swap(a[i],a[i+1]);	
		}
		else
		{
			for(i=2;i<n;i+=2)
			swap(a[i],a[i+1]);
		}
		for(i=1;i<=n;i++)
		cout<<a[i]<<" ";
		cout<<endl;
	}
	return 0;
}
