#include <bits/stdc++.h>

using namespace std;
using ll = long long;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int test = 1;
    cin >> test;

    while (test--) {
        int n;
        cin >> n;

        vector<ll> a(n);

        for (int i = 0; i < n; ++i) {
            cin >> a[i];
        }

        stable_partition(a.begin(), a.end(), [&](ll x) { return x % 4; });

        for (int t = 0; t < 2; ++t) {
            while (size(a) > 1 && (t || a.back() % 4 == a.end()[-2] % 4)) {
                cout << a.back() << " " << a.end()[-2] << '\n';
                a.end()[-2] = (a.end()[-2] + a.back()) / 2;
                a.pop_back();
            }
            reverse(a.begin(), a.end());
        }
    }

    return 0;
}