import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.io.BufferedInputStream;
import java.util.PriorityQueue;
import java.util.HashSet;
import java.util.AbstractCollection;
import java.io.FilterInputStream;
import java.io.InputStream;

/**
 * @author khokharnikunj8
 */

public class Main {
    public static void main(String[] args) {
        new Thread(null, new Runnable() {
            public void run() {
                new Main().solve();
            }
        }, "1", 1 << 26).start();
    }

    void solve() {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        ScanReader in = new ScanReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        DIntersectingSubtrees solver = new DIntersectingSubtrees();
        int testCount = in.scanInt();
        for (int i = 1; i <= testCount; i++)
            solver.solve(i, in, out);
        out.close();
    }

    static class DIntersectingSubtrees {
        int[][] G;
        HashSet<Integer> set1;
        HashSet<Integer> set2;
        int[] dist;

        private void dijkstra(int node) {
            PriorityQueue<pair> priorityQueue = new PriorityQueue<>();
            priorityQueue.add(new pair(0, node));
            while (!priorityQueue.isEmpty()) {
                pair tt = priorityQueue.poll();
                if (dist[tt.y] != 1000000000) continue;
                dist[tt.y] = tt.x;
                for (int i : G[tt.y]) {
                    if (tt.x + 1 < dist[tt.y]) priorityQueue.add(new pair(tt.x + 1, i));
                }
            }
        }

        public void solve(int testNumber, ScanReader in, PrintWriter out) {
            int n = in.scanInt();
            int[] from = new int[n - 1];
            int[] to = new int[n - 1];
            for (int i = 0; i < n - 1; i++) {
                from[i] = in.scanInt();
                to[i] = in.scanInt();
            }
            G = CodeHash.packGraph(from, to, n);
            set1 = new HashSet<>();
            set2 = new HashSet<>();
            int k1 = in.scanInt();
            int[] ar1 = new int[k1];
            for (int i = 0; i < k1; i++) set1.add(ar1[i] = in.scanInt());
            int k2 = in.scanInt();
            int[] ar2 = new int[k1];
            for (int i = 0; i < k2; i++) set2.add(ar2[i] = in.scanInt());
            dist = new int[n + 1];
            Arrays.fill(dist, 1000000000);
            out.println("B " + ar2[0]);
            out.flush();
            int nodd = in.scanInt();
            if (set1.contains(nodd)) {
                out.println("C " + nodd);
                out.flush();
                return;
            }
            dijkstra(nodd);
            int ans = 0;
            for (int i : set1) if (dist[i] < dist[ans]) ans = i;
            if (ans == 0) throw new RuntimeException();
            out.println("A " + ans);
            out.flush();
            int tl = in.scanInt();
            if (set2.contains(tl)) {
                out.println("C " + ans);
                out.flush();
            } else {
                out.println("-1");
                out.flush();
            }

        }

        class pair implements Comparable<pair> {
            int x;
            int y;

            public int compareTo(pair o) {
                return this.x - o.x;
            }

            public pair(int x, int y) {
                this.x = x;
                this.y = y;
            }

        }

    }

    static class CodeHash {
        public static int[][] packGraph(int[] from, int[] to, int n) {
            int[][] g = new int[n + 1][];
            int p[] = new int[n + 1];
            for (int i : from) p[i]++;
            for (int i : to) p[i]++;
            for (int i = 0; i <= n; i++) g[i] = new int[p[i]];
            for (int i = 0; i < from.length; i++) {
                g[from[i]][--p[from[i]]] = to[i];
                g[to[i]][--p[to[i]]] = from[i];
            }
            return g;
        }

    }

    static class ScanReader {
        private byte[] buf = new byte[4 * 1024];
        private int index;
        private BufferedInputStream in;
        private int total;

        public ScanReader(InputStream inputStream) {
            in = new BufferedInputStream(inputStream);
        }

        private int scan() {
            if (index >= total) {
                index = 0;
                try {
                    total = in.read(buf);
                } catch (Exception e) {
                    e.printStackTrace();
                }
                if (total <= 0) return -1;
            }
            return buf[index++];
        }

        public int scanInt() {
            int integer = 0;
            int n = scan();
            while (isWhiteSpace(n)) n = scan();
            int neg = 1;
            if (n == '-') {
                neg = -1;
                n = scan();
            }
            while (!isWhiteSpace(n)) {
                if (n >= '0' && n <= '9') {
                    integer *= 10;
                    integer += n - '0';
                    n = scan();
                }
            }
            return neg * integer;
        }

        private boolean isWhiteSpace(int n) {
            if (n == ' ' || n == '\n' || n == '\r' || n == '\t' || n == -1) return true;
            else return false;
        }

    }
}

