#include <iostream>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <vector>
#include <set>
#include <queue>
#include <map>
#include <iomanip>
#define endl '\n'
#define int long long
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define rep2(i,a,b) for(int i=(a);i>=(b);i--)
using namespace std;
template<typename T>
void cc(vector<T> tem) { for (auto x : tem) cout << x << ' '; cout << endl; }
void cc(int a) { cout << a << endl; }
void cc(int a, int b) { cout << a << ' ' << b << endl; }
void cc(int a, int b, int c) { cout << a << ' ' << b << ' ' << c << endl; }
void kuaidu() { ios::sync_with_stdio(false), cin.tie(0), cout.tie(0); }
inline int max(int a, int b) { if (a < b) return b; return a; }
inline int min(int a, int b) { if (a < b) return a; return b; }
void cmax(int& a, const int b) { if (b > a) a = b; }
void cmin(int& a, const int b) { if (b < a) a = b; }
using PII = pair<int, int>;
using i128 = __int128;

//--------------------------------------------------------------------------------
const int N = 1e5 + 10;
const int M = 1e6 + 10;
const int mod = 1e9 + 7;
const int INF = 1e16;
int n, m, T;
int zx, zy;
int tx, ty;
int A[4];//0 shang 1 xia 2 zuo 3 you
//--------------------------------------------------------------------------------
void shang() {
    rep(i, 1, A[0]) cout << 'U';
    rep(i, 1, A[1]) cout << 'D';
}
void zuo() {
    rep(i, 1, A[2]) cout << 'L';
    rep(i, 1, A[3]) cout << 'R';
}
signed main() {
    kuaidu();
    T = 1;
    cin >> T;
    while (T--) {
        cin >> zx >> zy;
        string s; cin >> s;
        rep(i, 0, 3) A[i] = 0;
        tx = 0, ty = 0;
        rep(i, 0, s.size() - 1) {
            if (s[i] == 'U') A[0]++, ty += 1;
            if (s[i] == 'L') A[2]++, tx -= 1;
            if (s[i] == 'D') A[1]++, ty -= 1;
            if (s[i] == 'R') A[3]++, tx += 1;
        }

        if (zx == 0 and zy == 0) {
            cout << "Impossible" << endl;
            continue;
        }

        if (zx == tx and zy == ty) {
            cout << "Impossible" << endl;
            continue;
        }

        
        if (zx and zy) {

            if (ty == zy) {
                zuo(), shang();
                cout << endl;

                continue;
            }

            if (tx == zx) {
                shang(), zuo();
                cout << endl;

                continue;
            }
            shang(); zuo();
            cout << endl;

            continue;
        }

        if (tx and ty) {
            if (zx == 0) {
                zuo(), shang();
                cout << endl;

                continue;
            }
            if (zy == 0) {
                shang(); zuo();
                cout << endl;

                continue;
            }
            continue;
        }
        
        if (zx and ty or zy and tx) {
            if (zx and ty) {
                shang(), zuo();
                cout << endl;

                continue;
            }
            if (zy and tx) {
                zuo(), shang();
                cout << endl;

                continue;
            }
        }

        if (zx) {

            if (zx * tx > 0 and abs(zx) > abs(tx) || zx * tx <= 0) {
                if (zx < 0) {
                    shang();
                    rep(i, 1, A[3]) cout << 'R';
                    rep(i, 1, A[2]) cout << 'L';
                }
                if (zx > 0) {
                    shang();
                    rep(i, 1, A[2]) cout << 'L';
                    rep(i, 1, A[3]) cout << 'R';
                }
                cout << endl;

                continue;
            }

            if (!A[0]) {
                cout << "Impossible" << endl;
                continue;
            }
            //0 shang 1 xia 2 zuo 3 you
            cout << 'U';
            zuo();
            rep(i, 2, A[0]) cout << 'U';
            rep(i, 1, A[1]) cout << 'D';
            cout << endl;

            continue;
        }

        if (zy) {

            if (zy * ty > 0 and abs(zy) > abs(ty) or zy * ty <= 0) {
                if (zy < 0) {
                    zuo();
                    rep(i, 1, A[0]) cout << 'U';
                    rep(i, 1, A[1]) cout << 'D';
                }
                if (zy > 0) {
                    zuo();
                    rep(i, 1, A[1]) cout << 'D'; rep(i, 1, A[0]) cout << 'U';
                }
                cout << endl;

                continue;
            }
            if (!A[2]) {
                cout << "Impossible" << endl;
                continue;
            }
            cout << 'L';
            shang();
            rep(i, 2, A[2]) cout << 'L';
            rep(i, 1, A[3]) cout << 'R';
            cout << endl;
            continue;
        }


    }
    return 0;
}