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 int[][] get = new int[25][5];
    public static void solve(){
        int mx = scanner.nextInt();
        int my = scanner.nextInt();
        String str = scanner.nextLine();n = str.length();
        int[] cnt = new int[5];
        int inx = 0;
        int iny = 0;
        for(int i = 0 ; i < n ; i++){
            char ch = str.charAt(i);
            if(ch == 'L') {
                cnt[1]++;
                inx--;
            } else if(ch == 'R') {
                cnt[2]++;
                inx++;
            } else if(ch == 'D') {
                cnt[3]++;
                iny--;
            } else {
                cnt[4]++;
                iny++;
            }
        }
        //特判
        if(mx == 0 && my == 0) {out.println("Impossible");return;}
        if(inx == mx && iny == my) {out.println("Impossible");return;}

        for(int i = 1 ; i <= 24 ; i++){
            inx = 0;iny = 0;
            boolean pool = true;
            StringBuilder ans = new StringBuilder();
            int a = cnt[get[i][1]];char ch1 = getch(get[i][1]);
            int b = cnt[get[i][2]];char ch2 = getch(get[i][2]);
            int c = cnt[get[i][3]];char ch3 = getch(get[i][3]);
            int d = cnt[get[i][4]];char ch4 = getch(get[i][4]);
            while(a -- != 0){
                ans.append(ch1);
                if(ch1 == 'L') inx--;
                if(ch1 == 'R') inx++;
                if(ch1 == 'U') iny++;
                if(ch1 == 'D') iny--;
                if(inx == mx && iny == my) {
                    pool = false;
                    break;
                }
            } if(!pool) continue;

            while(b -- != 0){
                ans.append(ch2);
                if(ch2 == 'L') inx--;
                if(ch2 == 'R') inx++;
                if(ch2 == 'U') iny++;
                if(ch2 == 'D') iny--;
                if(inx == mx && iny == my) {
                    pool = false;
                    break;
                }
            } if(!pool) continue;

            while(c -- != 0){
                ans.append(ch3);
                if(ch3 == 'L') inx--;
                if(ch3 == 'R') inx++;
                if(ch3 == 'U') iny++;
                if(ch3 == 'D') iny--;
                if(inx == mx && iny == my) {
                    pool = false;
                    break;
                }
            } if(!pool) continue;

            while(d -- != 0){
                ans.append(ch4);
                if(ch4 == 'L') inx--;
                if(ch4 == 'R') inx++;
                if(ch4 == 'U') iny++;
                if(ch4 == 'D') iny--;
                if(inx == mx && iny == my) {
                    pool = false;
                    break;
                }
            } if(!pool) continue;
            out.println(ans);
            return;
        }
        out.println("Impossible");
    }
    public static void init(){
        int in = 1;
        for(int i = 1 ; i <= 4 ; i++){
            for(int j = 1 ; j <= 4 ; j++){
                for(int o = 1 ; o <= 4 ; o++){
                    for(int p = 1 ; p <= 4 ; p++){
                        if(i != j && i != o && i != p && j != o && j != p && o != p){
                            get[in][1] = i;
                            get[in][2] = j;
                            get[in][3] = o;
                            get[in][4] = p;
                            in++;
                        }
                    }
                }
            }
        }
    }
    public static char getch(int nu){
        if(nu == 1) return 'L';
        if(nu == 2) return 'R';
        if(nu == 3) return 'D';
        return 'U';
    }
    public static void main(String[] args) {
        init();
//        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));
    }
}