#include <bits/stdc++.h>
using namespace std;
long long power(long long x, long long y);
long long mpower(long long x, long long y, long long p);
long long modInv(long long a, long long m);
long long gcdExtended(long long a, long long b, long long *x, long long *y);
bool isPrime(long long n);
vector<long long> A[1005];
long long vis[1005], lvl[1005], vis2[1005], lvl2[1005];
void ini(long long n) {
  for (int i = 0; i <= n; i++) {
    A[i].clear();
    vis[i] = 0;
    lvl[i] = 0;
    vis2[i] = 0;
    lvl2[i] = 0;
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long t, i, j, k, l, h, p, q, r, x, y, z, a, b, c, d, f, n, m,
      M = 1000000007;
  char ch, ch2, ch3;
  string s, s1, s2, s3;
  set<long long> S;
  cin >> t;
  while (t--) {
    cin >> n;
    ini(n);
    for (i = 1; i < n; i++) {
      cin >> x >> y;
      A[x].push_back(y);
      A[y].push_back(x);
    }
    cout << "? " << n << " ";
    for (i = 1; i <= n; i++) {
      cout << i << " ";
    }
    cout << endl;
    cin >> x >> y;
    z = y;
    queue<long long> Q;
    Q.push(x);
    vis[x] = 1;
    lvl[x] = 0;
    while (Q.size()) {
      x = Q.front();
      Q.pop();
      for (i = 0; i < A[x].size(); i++) {
        if (!vis[A[x][i]]) {
          vis[A[x][i]] = 1;
          lvl[A[x][i]] = lvl[x] + 1;
          Q.push(A[x][i]);
        }
      }
    }
    l = z / 2;
    h = z;
    a = 0;
    b = 0;
    while (l <= h) {
      m = (l + h + 1) / 2;
      vector<long long> v;
      for (i = 1; i <= n; i++) {
        if (lvl[i] == m) {
          v.push_back(i);
        }
      }
      if (v.size() == 0) {
        h = m - 1;
        continue;
      }
      cout << "? " << v.size() << " ";
      for (i = 0; i < v.size(); i++) {
        cout << v[i] << " ";
      }
      cout << endl;
      cin >> x >> y;
      if (y == z) {
        l = m + 1;
        a = x;
        b = y;
      } else {
        h = m - 1;
      }
    }
    x = a;
    y = b;
    long long ans = x;
    vis2[x] = 1;
    lvl2[x] = 0;
    Q.push(x);
    while (Q.size()) {
      x = Q.front();
      Q.pop();
      for (i = 0; i < A[x].size(); i++) {
        if (!vis2[A[x][i]]) {
          vis2[A[x][i]] = 1;
          lvl2[A[x][i]] = lvl2[x] + 1;
          Q.push(A[x][i]);
        }
      }
    }
    vector<long long> v;
    for (i = 1; i <= n; i++) {
      if (lvl2[i] == z) {
        v.push_back(i);
      }
    }
    cout << "? " << v.size() << " ";
    for (i = 0; i < v.size(); i++) {
      cout << v[i] << " ";
    }
    cout << endl;
    cin >> x >> y;
    cout << "! " << ans << " " << x << endl;
    cin >> s;
  }
  return 0;
}
long long modInv(long long a, long long m) {
  long long x, y;
  long long g = gcdExtended(a, m, &x, &y);
  long long res = (x % m + m) % m;
  return res;
}
long long gcdExtended(long long a, long long b, long long *x, long long *y) {
  if (a == 0) {
    *x = 0, *y = 1;
    return b;
  }
  long long x1, y1;
  long long gcd = gcdExtended(b % a, a, &x1, &y1);
  *x = y1 - (b / a) * x1;
  *y = x1;
  return gcd;
}
long long mpower(long long x, long long y, long long p) {
  long long res = 1;
  x = x % p;
  while (y > 0) {
    if (y & 1) res = (res * x) % p;
    y = y >> 1;
    x = (x * x) % p;
  }
  return res;
}
long long power(long long x, long long y) {
  long long res = 1;
  while (y > 0) {
    if (y & 1) res = res * x;
    y = y >> 1;
    x = x * x;
  }
  return res;
}
bool isPrime(long long n) {
  if (n <= 1) return false;
  if (n <= 3) return true;
  if (n % 2 == 0 || n % 3 == 0) return false;
  long long p = sqrt(n);
  for (int i = 5; i <= p; i = i + 6)
    if (n % i == 0 || n % (i + 2) == 0) return false;
  return true;
}
