#include<iostream>
#include<cstring>
#include<algorithm>
using namespace std;
int a[60];
int main(){
	int t;
	cin>>t;
	while(t--){
		int n;
		cin>>n;
		memset(a,0,sizeof(a));
		for(int i=1;i<=2*n;++i){
			cin>>a[i];
		}
		sort(a+1,a+2*n+1);
		for(int i=1;i<=n;i++){
			cout<<a[i+n]<<" "<<a[i]<<" ";
		}
		cout<<endl;
	}
} 