#include <bits/stdc++.h>
#include <random>

using namespace std;

typedef unsigned long long ull;
typedef long long ll;
typedef double ld;
//#define ll __int128
//#define int ll
//#define int ll
//#define char ll
typedef vector<char> vc;
typedef vector<vc> vvc;
typedef vector<vvc> vvvc;
typedef pair<int, int> pii;
typedef pair<pii, pii> piii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<pii> vpi;
typedef vector< vi > vvi;
typedef vector< vvi > vvvi;
typedef vector<short> vs;
typedef vector<vs> vvs;
typedef vector<vvs> vvvs;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<vvl> vvvl;
typedef vector<ld> vld;
typedef vector<vld> vvld;
typedef vector<vvld> vvvld;
typedef vector<string> vst;
typedef vector<vst> vvst;
typedef pair<ld, ld> pld;

#define inmin(a, b) a = min(a, (b))
#define inmax(a, b) a = max(a, (b))
#define ALL(a) a.begin(),a.end()
#define RALL(a) a.rbegin(),a.rend()
#define sqr(x) ((x) * (x))
#define fori(i, n) for(int i = 0; i < int(n); ++i)
#define SZ(a) ((int)((a).size()))
#define triple(T) tuple<T, T, T>
#define quad(T) tuple<T, T, T, T>
#define watch(x) cerr << (#x) << " = " << (x) << endl;

#ifdef MAX_HOME
#define cerr cout
#else
#define cerr if (false) cerr
#endif

const double PI = 2 * acos(0.0);
#define rand shittttty_shit
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
mt19937_64 rng_64(chrono::steady_clock::now().time_since_epoch().count());

const string DIGITS = "0123456789";
const string ALPH = "abcdefghijklmnopqrstuvwxyz";


template <class T0, class T1>
inline ostream & operator << (ostream &out, pair<T0, T1> &a) {
    return out << "{" << a.first << ", " << a.second << "}";
}

template <class T0, class T1>
inline istream & operator >> (istream &in, pair<T0, T1> &a) {
    return in >> a.first >> a.second;
}

template <class T0, class T1, class T2>
inline ostream & operator << (ostream &out, tuple<T0, T1, T2> &a) {
    return out << "{" << get<0>(a) << ", " << get<1>(a) << ", " << get<2>(a) << "}";
}

template <class T0, class T1, class T2, class T3>
inline ostream & operator << (ostream &out, tuple<T0, T1, T2, T3> &a) {
    return out << "{" << get<0>(a) << ", " << get<1>(a) << ", " << get<2>(a) << ", " <<  get<3>(a) << "}";
}

template<class T>
inline ostream & operator << (ostream &out, vector<T> &a) {
    out << "[";
    fori (i, a.size())
        out << a[i] << vector<string>{", ", "]  "}[i + 1 == a.size()];
    return out;
}


void smain();



signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
#ifdef MAX_HOME
    freopen("input.txt", "r", stdin);
    clock_t start = clock();
#endif
    cout << setprecision(4) << fixed;
    smain();
#ifdef MAX_HOME
    cout << "\n\n\n\nTOTAL EXECUTION TIME: " << float( clock () - start ) /  CLOCKS_PER_SEC << endl;
#endif
    return 0;
}


string solve(int a, int b, int L, int R) {
    int x = (a + b) / (b + 1);

    int l = 0;
    int r = b + 1;
    int cx, y;
    int resta = 0, restb = 0;
    if (a % (b + 1) == 0) {
        cx = b + 1;
        goto fin;
    }

    l = 0, r = min(b + 1, a / x + 1);

    while (r - l > 1) {
        int mx = r + l >> 1;
        int s = a - mx * x;
        int f = b - mx + 1;
        if ((f + s) / (s + 1) <= x) {
            l = mx;
        } else {
            r = mx;
        }
    }
    cx = l;

    l = 0, r = min(x, a - cx * x) + 1;

    while (r - l > 1) {
        int my = r + l >> 1;
        int s = a - cx * x - my;
        int f = b - cx;
        if ((f + s) / (s + 1) <= x) {
            l = my;
        } else {
            r = my;
        }
    }

    y = l;

    resta = a - cx * x - y;
    restb = b - cx - resta * x;
//    watch(restb);


    fin:string s = "";
    for (int i = L; i <= R; ++i) {
        int cur = i;
        if (cx * (x + 1) > cur) {
            if (cur % (x + 1) == x) {
                s += "B";
            } else {
                s += "A";
            }
            continue;
        }
        cur -= cx * (x + 1);
        if (y > cur) {
            s += "A";
            continue;
        }
        cur -= y;

        if (restb > cur) {
            s += "B";
            continue;
        }
        cur -= restb;

        if (cur % (x + 1) == 0) {
            s += "A";
        } else {
            s += "B";
        }
    }

    return s;
}

int get(string s) {
    int cnt = 1;
    int ret = 1;
    for (int i = 1; i < SZ(s); ++i) {
        if (s[i] == s[i - 1]) {
            cnt++;
        } else {
            cnt = 1;
        }
        inmax(ret, cnt);
    }
    return ret;
}

string naive(int a, int b) {
    string s(a + b, 'B');
    fori (i, a) {
        s[i] = 'A';
    }
    sort(ALL(s));
    int x = get(s);
    string ans = s;
    do {
        int cx = get(s);
        if (cx < x || (cx == x && s < ans)) {
            ans = s;
            x = cx;
        }
    } while (next_permutation(ALL(s)));
    return ans;
}

void stress() {
    int cnt = -1;
    while (true) {
        if (++cnt % 20 == 0)
            watch(cnt);
        int a = rng() % 10 + 1, b = rng() % 10 + 1;
        if (a < b)
            swap(a, b);
        string nv = naive(a, b);
        string sl = solve(a, b, 0, a + b - 1);
        if (nv != sl) {
            watch(cnt);
            watch(nv);
            watch(sl);
            cout << a << ' ' << b << ' ' << 1 << ' ' << a + b << endl;
            return;
        }
    }
}


void smain() {

//    stress();
//    return;

    int q;
    cin >> q;

    while (q--) {
        int a, b, l, r;
        cin >> a >> b >> l >> r;
        l--, r--;
        string s;
        if (a >= b) {
            s = solve(a, b, l, r);
//            watch(naive(a, b));
        } else {
            swap(a, b);
            l = a + b - l - 1;
            r = a + b - r - 1;
//            cerr << "(" << l << ", " << r << ")" << endl;
            s = solve(a, b, r, l);
//            watch(s);
            reverse(ALL(s));
            for (auto & x : s) {
                if (x == 'A')
                    x = 'B';
                else
                    x = 'A';
            }
        }
        cout << s << '\n';
    }

}

Measured memory_bytes: 384