#include <bits/stdc++.h>
using namespace std;

const int N = 2e5 + 5;
int f[N], cen[N], p[N], siz[N];

int getf(int x) { return f[x] == x ? x : f[x] = getf(f[x]); }

void work() {
    int n; cin >> n;
    vector < vector <int> > a(n + 1);
    vector < vector <int> > E(n + 1);
    for (int i = 1; i <= n; i++) {
        int x; cin >> x;
        for (int j = 0; j < x; j++) {
            int y; cin >> y;
            a[i].push_back(y);
        }
    }
    for (int i = 1; i <= n; i++) f[i] = i;
    for (int i = n; i >= 1; i--) {
        siz[i] = 1;
        if (!a[i].size()) {
            // cen[i] = i;
            continue;
        }
        for (auto y : a[i]) {
            int r = getf(y);
            f[r] = i;
            p[r] = i;
            siz[i] += siz[r];
            E[i].push_back(r);
        }
        /*int large = 0, who = -1;
        for (auto y : E[i]) {
            if (siz[y] > large) {
                large = y;
                who = y;
            }
        }
        while (who != i) {
            if (siz[who] >= siz[i] - siz[who]) break;
            who = p[who];
        }
        cen[i] = who;*/
    }
    for (int i = 1; i <= n; i++) {
        for (auto y : E[i]) {
            if (y > i) {
                cout << i << ' ' << y << '\n';
            }
        }
    }
}

int main() {
    ios::sync_with_stdio(0); cin.tie(0);
    int T; cin >> T;
    while (T--) work();
}