#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];
        }


        auto cmp = [&](ll x, ll y) {
            return pair{x % 4, x} < pair{y % 4, y};
        };

        multiset<ll, decltype(cmp)> st(a.begin(), a.end(), cmp);

        while (size(st) > 1) {
            ll f = *st.begin(), s = *++st.begin();
            if ((f + s) / 2 % 2 == 1) {
                f = *st.rbegin(), s = *++st.rbegin();
            }
            cout << f << " " << s << '\n';
            st.extract(f);
            st.extract(s);
            st.insert((f + s) / 2);
        }
    }

    return 0;
}