#include <bits/stdc++.h>
using namespace std;
clock_t start;
mt19937_64 rng(chrono::system_clock::now().time_since_epoch().count());
template <typename T>
void _F(const char *name, T arg1) {
  cerr << name << " = " << arg1 << endl;
}
template <typename T, typename... Args>
void _F(const char *names, T arg1, Args... args) {
  const char *name = strchr(names, ',');
  cerr.write(names, name - names) << " = " << arg1 << endl;
  _F(name + 2, args...);
}
template <typename T1, typename T2>
istream &operator>>(istream &in, pair<T1, T2> &q) {
  in >> q.first >> q.second;
  return in;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &out, pair<T1, T2> &q) {
  out << q.first << " " << q.second;
  return out;
}
template <typename T1, typename T2>
pair<T1, T2> operator+(pair<T1, T2> p1, pair<T1, T2> p2) {
  return {p1.first + p2.first, p1.second + p2.second};
}
template <typename T1, typename T2>
pair<T1, T2> operator-(pair<T1, T2> p1, pair<T1, T2> p2) {
  return {p1.first - p2.first, p1.second - p2.second};
}
template <typename T1, typename T2>
bool operator<(pair<T1, T2> p1, pair<T1, T2> p2) {
  return p1 < p2;
}
template <typename T>
void Unique(vector<T> &v) {
  sort((v).begin(), (v).end()),
      v.resize(distance(v.begin(), unique((v).begin(), (v).end())));
}
const long long N = 1e3 + 1;
std::vector<long long> g[N], hh[N], vis(N);
long long tin[N], tout[N], t, par[N];
long long n, cnt;
void dfs(long long v, long long h) {
  vis[v] = 1;
  tin[v] = (++t);
  hh[h].push_back(v);
  for (auto u : g[v]) {
    if (!vis[u]) par[u] = v, dfs(u, h + 1);
  }
  tout[v] = (++t);
}
pair<long long, long long> Query(std::vector<long long> &q) {
  if (!(long long)((q).size())) return make_pair(-1, -1);
  assert(cnt < 14);
  std::vector<long long> v = q, x = q;
  Unique(x);
  sort((v).begin(), (v).end());
  assert(v == x);
  cnt++;
  cout << "? " << (long long)((q).size()) << endl;
  for (auto u : q) cout << u << " ";
  cout << endl;
  q.clear();
  pair<long long, long long> ans;
  cin >> ans;
  return ans;
}
void solve(long long &test) {
  cnt = 0;
  cin >> n;
  for (long long i = 0; i < n - 1; i++) {
    long long u, v;
    cin >> u >> v;
    g[u].push_back(v);
    g[v].push_back(u);
  }
  std::vector<long long> q;
  for (long long i = 1; i <= n; i++) {
    q.push_back(i);
  }
  pair<long long, long long> ans1 = Query(q);
  q.clear();
  for (auto u : g[ans1.first]) {
    q.push_back(u);
  }
  pair<long long, long long> ans2 = Query(q);
  q.clear();
  dfs(ans1.first, 0);
  pair<long long, long long> sure_ans = make_pair(ans1.first, 0);
  if (ans2.second == ans1.second) {
    long long s = 1, e = n;
    while (s <= e) {
      long long m = (s + e) >> 1;
      for (auto u : hh[m]) {
        if (tin[u] >= tin[ans2.first] && tout[u] <= tout[ans2.first]) {
          q.push_back(u);
        }
      }
      pair<long long, long long> ans = Query(q);
      q.clear();
      if (ans.second == ans1.second) {
        s = m + 1;
        sure_ans = make_pair(ans.first, m);
      } else {
        e = m - 1;
      }
    }
  }
  set<long long> s;
  long long cur = sure_ans.first;
  while (cur != ans1.first) {
    s.insert(cur);
    cur = par[cur];
  }
  long long h = ans1.second - sure_ans.second;
  for (auto u : hh[h]) {
    if (u != sure_ans.first && s.find(u) == end(s)) q.push_back(u);
  }
  cout << "! " << sure_ans.first << " " << Query(q).first << endl;
  string tmp;
  cin >> tmp;
  for (long long i = 0; i <= n; i++) {
    g[i].clear(), hh[i].clear(), vis[i] = 0;
  }
  t = 0;
}
signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long t = 1;
  start = clock();
  cout << fixed << setprecision(20);
  cin >> t;
  for (long long i = 1; i <= t; ++i) {
    solve(i);
  }
  return 0;
}
