#include<bits/stdc++.h>
#define poly vector<int>
#define IOS ios::sync_with_stdio(false)
#define ll long long
#define mp make_pair
#define mt make_tuple
#define pa pair < int,int >
#define fi first
#define se second
#define inf 1e18
#define mod 998244353
#define sz(x) (int)((x).size())
#define int ll
//#define N
using namespace std;
poly a[2];
int n;
vector<pa>ans;
int ex=0;
void dfs(poly g)
{
	if (sz(g)==1)
	{
		ex=1;
		return;
	}
	for (int i=0;i<sz(g);i++)
		for (int j=i+1;j<sz(g);j++)
		if ((g[i]+g[j])%2==0)
		{
			poly nxt=g;
			ans.push_back(mp(g[i],g[j]));
			g[i]+=g[j];g[i]>>=1;
			swap(g[j],g.back());
			g.pop_back();
			dfs(g);
			if (ex) return;
			ans.pop_back();
			g=nxt;
		}
}			
void work(int j)
{
	// cout<<sz(a[0])<<" "<<sz(a[1])<<endl;
	// cout<<"work "<<j<<endl;
	int x=a[j].back();a[j].pop_back();
	int y=0;
	for (int i=0;i<sz(a[j]);i++)
		if ((x&3)!=(a[j][i]&3))
		{
			swap(a[j][i],a[j].back());
			y=a[j].back();
			a[j].pop_back();
			break;
		}
	if ((y&3)<(x&3)) swap(x,y);
	while (a[0].size()>=2||a[1].size()>=2)
	{
		for (int i=0;i<2;i++)
			while (a[i].size()>=2)
			{
				int op=a[i].back()+a[i][sz(a[i])-2];
				ans.push_back({a[i].back(),a[i][sz(a[i])-2]});
				a[i].pop_back();
				a[i].pop_back();
				op>>=1;
				a[op&1].push_back(op);
			}
	}
	poly all;
	all.push_back(x);
	all.push_back(y);
	for (auto u:a[0]) all.push_back(u);
	for (auto u:a[1]) all.push_back(u);
	ex=0;
	dfs(all);
}					
void BellaKira()
{
	cin>>n;
	for (int i=1;i<=n;i++)
	{
		int x;
		cin>>x;
		// x%=5;
		a[x%2].push_back(x);
	}
	while (sz(a[0])+sz(a[1])>1)
	{
		bool ex=0;
		int lst=sz(ans);
		for (int j=0;j<2;j++)
			if (sz(a[j]))
			{
				poly nxt;
				int hi=-1;
				for (int t=0;t<60;t++)
				{
					bool bl=1;
					for (auto u:a[j])
						bl&=((u>>t)&1)==((a[j].back()>>t)&1);
					if (bl) continue;
					hi=t;
					break;
				}
				// cout<<"!!"<<j<<" "<<hi<<'\n';
				if (hi==-1)
				{
					if (sz(a[j])>1)
					{
						while (sz(a[j])>1) 
						{
							a[j].pop_back();
							ans.push_back(mp(a[j][0],a[j][0]));
						}
					}
					continue;
				}
				if (hi==1)
				{
					work(j);ex=1;
					break;
				}
				int t=hi;
				for (int i=0;i<sz(a[j]);i++)
					if (((a[j][i]>>t)&1)!=((a[j].back()>>t)&1))
					{
						ans.push_back(mp(a[j][i],a[j].back()));
						a[j][i]+=a[j].back();
						a[j].pop_back();
						a[j][i]>>=1;
						break;
					}
			}
		if (ex==1) break;
		if (lst==sz(ans))
		{
			cout<<"-1\n";
			poly().swap(a[0]);
			poly().swap(a[1]);
			vector<pa>().swap(ans);
			return;
		}
	}
	// assert(sz(ans)==n-1);
	for (auto [u,v]:ans)
	{
		cout<<u<<" "<<v<<'\n';
		// assert((u+v)%2==0);
	}
	// fflush(stdout);
	poly().swap(a[0]);
	poly().swap(a[1]);
	vector<pa>().swap(ans);
}
signed main()
{
	IOS;
	cin.tie(0);
	int T=1;
	cin>>T;
	while (T--)
	{
		BellaKira();
	}
}