#include <bits/stdc++.h>
#pragma GCC optimize("O3", "unroll-loops")
using namespace std;
template <class T>
inline void sort(T &a) {
  sort((a).begin(), (a).end());
}
template <class T>
inline void rsort(T &a) {
  sort((a).rbegin(), (a).rend());
}
template <class T>
inline void reverse(T &a) {
  reverse((a).begin(), (a).end());
}
template <class T, class U>
inline void checkmin(T &x, U y) {
  if (x > y) x = y;
}
template <class T, class U>
inline void checkmax(T &x, U y) {
  if (x < y) x = y;
}
vector<vector<int>> rev, G;
void dfs(int v, int p = -1) {
  for (auto &i : G[v])
    if (i != p) {
      rev[i].push_back(v);
      dfs(i, v);
    }
}
void solve() {
  int n;
  cin >> n;
  G = vector<vector<int>>(n);
  for (int i = 1; i < n; ++i) {
    int u, v;
    cin >> u >> v;
    --u, --v;
    G[u].push_back(v);
    G[v].push_back(u);
  }
  int k1, k2;
  cin >> k1;
  vector<int> arr(k1);
  for (auto &i : arr) cin >> i, --i;
  cin >> k2;
  vector<int> brr(k2);
  for (auto &i : brr) cin >> i, --i;
  vector<bool> used(n);
  for (auto &i : arr) used[i] = true;
  cout << "B " << brr[0] + 1 << endl;
  int y;
  cin >> y;
  --y;
  rev = vector<vector<int>>(n);
  dfs(y);
  y = arr[0];
  while (int(rev[y].size())) {
    if (!used[rev[y][0]]) break;
    y = rev[y][0];
  }
  int start = y;
  cout << "A " << y + 1 << endl;
  cin >> y;
  --y;
  for (auto i : brr)
    if (i == y) {
      cout << "C " << start + 1 << endl;
      return;
    }
  cout << "C " << -1 << endl;
}
signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cout << fixed << setprecision(20);
  srand(time(nullptr));
  int q;
  cin >> q;
  while (q--) solve();
  return 0;
}
