import java.io.*;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.*;

public class Main {
    public static Read scanner = new Read(System.in);
    public static final long MOD = (long) (1e9 + 7);
    public static final int MID = (int) (4 * 1e1 + 7);
    public static final long LMAX = Long.MAX_VALUE;
    public static final long LMIN = Long.MIN_VALUE;
    public static final int IMAX = Integer.MAX_VALUE;
    public static final int IMIN = Integer.MIN_VALUE;
    public static int[] arr = new int[MID];
    //    public static long[] Qz = new long[MID];
//    public static long[] Hz = new long[MID];
    public static int N, M , n , m;
    public static long ans;
    //    public static boolean[][] stack = new boolean[MID][MID];
    //四个方向
    public static int[] row = {1, -1, 0, 0};
    public static int[] cos = {0, 0, 1, -1};
    static PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
    public static void solve(){
        int mx = scanner.nextInt();
        int my = scanner.nextInt();
        String str = scanner.nextLine();n = str.length();
        int l = 0;
        int r = 0;
        int u = 0;
        int d = 0;
        int inx = 0;
        int iny = 0;
        for(int i = 0 ; i < n ; i++){
            char ch = str.charAt(i);
            if(ch == 'L') {
                l++;
                inx--;
            } else if(ch == 'R') {
                r++;
                inx++;
            } else if(ch == 'D') {
                d++;
                iny--;
            } else {
                u++;
                iny++;
            }
        }
        //特判
        if(mx == 0 && my == 0) {out.println("Impossible");return;}
        if(inx == mx && iny == my) {out.println("Impossible");return;}
        if(l > 0 && r == 0 && u == 0 && d == 0 && (l >= -mx && my == 0 && mx < 0)) {out.println("Impossible");return;}
        if(l > 0 && r == 0 && u == 0 && d == 0) {out.println(str);return;}
        if(r > 0 && l == 0 && u == 0 && d == 0 && (r >= mx && my == 0 && mx > 0)) {out.println("Impossible");return;}
        if(r > 0 && l == 0 && u == 0 && d == 0) {out.println(str);return;}
        if(u > 0 && l == 0 && r == 0 && d == 0 && (u >= my && mx == 0 && my > 0)) {out.println("Impossible");return;}
        if(u > 0 && l == 0 && r == 0 && d == 0) {out.println(str);return;}
        if(d > 0 && l == 0 && r == 0 && u == 0 && (d >= -my && mx == 0 && my < 0)) {out.println("Impossible");return;}
        if(d > 0 && l == 0 && r == 0 && u == 0) {out.println(str);return;}


        //有正解..
        ArrayList<Character> list = new ArrayList<>();
        for(int i = 0 ; i < n ; i++) list.add(str.charAt(i));
        for(int i = 1 ; i <= 10 ; i++){
            boolean pool = true;
            inx = 0;iny = 0;
            for(int j = 0 ; j < n ; j++){
                char ch = list.get(j);
                if(ch == 'L') {
                    l++;
                    inx--;
                } else if(ch == 'R') {
                    r++;
                    inx++;
                } else if(ch == 'D') {
                    d++;
                    iny--;
                } else {
                    u++;
                    iny++;
                }
                if(inx == mx && iny == my) {
                    pool = false;
                    break;
                }
            }
            if(pool){
               for(int j = 0 ; j < n ; j++) out.print(list.get(j));
               out.println();
            }
            Collections.shuffle(list);
        }

    }
    public static void main(String[] args) {

//        long start = System.currentTimeMillis();//程序开始时间戳
        int T = scanner.nextInt();
        while (T-- != 0) {
            solve();
        }
        out.flush();
//        long end = System.currentTimeMillis();//程序结束时间戳
//        out.println("运行时间 : " + (end - start));//输出运行时间
    }
    //快读
    static class Read {
        BufferedReader br;
        StringTokenizer st;

        public Read(InputStream in) {
            br = new BufferedReader(new InputStreamReader(in), 16384);
            eat("");
        }

        public void eat(String s) {
            st = new StringTokenizer(s);
        }

        public String nextLine() {
            try {
                return br.readLine();
            } catch (IOException e) {
                return null;
            }
        }

        public boolean hasNext() {
            while (!st.hasMoreTokens()) {
                String s = nextLine();
                if (s == null)
                    return false;
                eat(s);
            }
            return true;
        }

        public String next() {
            hasNext();
            return st.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

        public Double nextDouble() {
            return Double.parseDouble(next());
        }

        public BigInteger nextBigInteger() {
            return new BigInteger(next());
        }

        public BigDecimal nextBigDecimal() {
            return new BigDecimal(next());
        }
    }
    public static void swap(long[] arr , int index1 , int index2){
        long t = arr[index1];
        arr[index1] = arr[index2];
        arr[index2] = t;
    }
    public static long Dot_pitch(long x , long y , long xx , long yy){
        return (xx - x) * (xx - x) + (yy - y) * (yy - y);
//        return (long) Math.sqrt(Math.pow(xx - x , 2) + Math.pow(yy - y , 2));
    }
}