#include <bits/stdc++.h>
#define MP make_pair
#define PB push_back
#define int long long
#define st first
#define nd second
#define rd third
#define FOR(i, a, b) for(int i =(a); i <=(b); ++i)
#define RE(i, n) FOR(i, 1, n)
#define FORD(i, a, b) for(int i = (a); i >= (b); --i)
#define REP(i, n) for(int i = 0;i <(n); ++i)
#define VAR(v, i) __typeof(i) v=(i)
#define FORE(i, c) for(VAR(i, (c).begin()); i != (c).end(); ++i)
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) ((int)(x).size())
using namespace std;
template<typename TH> void _dbg(const char* sdbg, TH h) { cerr<<sdbg<<"="<<h<<"\n"; }
template<typename TH, typename... TA> void _dbg(const char* sdbg, TH h, TA... t) {
  while(*sdbg != ',')cerr<<*sdbg++; cerr<<"="<<h<<","; _dbg(sdbg+1, t...);
}
#ifdef LOCAL
#define debug(...) _dbg(#__VA_ARGS__, __VA_ARGS__)
#define debugv(x) {{cerr <<#x <<" = "; FORE(itt, (x)) cerr <<*itt <<", "; cerr <<"\n"; }}
#else
#define debug(...) (__VA_ARGS__)
#define debugv(x)
#define cerr if(0)cout
#endif
#define next ____next
#define prev ____prev
#define left ____left
#define hash ____hash
typedef long long ll;
typedef long double LD;
typedef pair<int, int> PII;
typedef pair<ll, ll> PLL;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<ll> VLL;
typedef vector<pair<int, int> > VPII;
typedef vector<pair<ll, ll> > VPLL;

template<class C> void mini(C&a4, C b4){a4=min(a4, b4); }
template<class C> void maxi(C&a4, C b4){a4=max(a4, b4); }
template<class T1, class T2>
ostream& operator<< (ostream &out, pair<T1, T2> pair) { return out << "(" << pair.first << ", " << pair.second << ")";}
template<class A, class B, class C> struct Triple { A first; B second; C third;
  bool operator<(const Triple& t) const { if (st != t.st) return st < t.st; if (nd != t.nd) return nd < t.nd; return rd < t.rd; } };
template<class T> void ResizeVec(T&, vector<int>) {}
template<class T> void ResizeVec(vector<T>& vec, vector<int> sz) {
  vec.resize(sz[0]); sz.erase(sz.begin()); if (sz.empty()) { return; }
  for (T& v : vec) { ResizeVec(v, sz); }
}
typedef Triple<int, int, int> TIII;
template<class A, class B, class C>
ostream& operator<< (ostream &out, Triple<A, B, C> t) { return out << "(" << t.st << ", " << t.nd << ", " << t.rd << ")"; }
template<class T> ostream& operator<<(ostream& out, vector<T> vec) { out<<"("; for (auto& v: vec) out<<v<<", "; return out<<")"; }
template<class T> ostream& operator<<(ostream& out, set<T> vec) { out<<"("; for (auto& v: vec) out<<v<<", "; return out<<")"; }
    
int32_t main() {

  ios_base::sync_with_stdio(0);
  cout << fixed << setprecision(10);
  cerr << fixed << setprecision(10);
  cin.tie(0);
  //double beg_clock = 1.0 * clock() / CLOCKS_PER_SEC;
  
  int q;
  cin>>q;
  RE (_, q) {
    int a, b, c, d;
    cin>>a>>b>>c>>d;
    int sw = 0;
    int n = a + b;
    if (a >= b) {
    } else {
      sw = 1;
      c = n - c + 1;
      d = n - d + 1;
      swap(a, b);
      swap(c, d);
    }
    int gr = (a + b) / (b + 1);
    int pref = 1, kl = 1, kp = n;
    while (kl <= kp) {
      int aktc = (kl + kp) / 2;
      int full_gr = aktc / (gr + 1);
      int rem_b = b - full_gr;
      int rem_a = a - (aktc - full_gr);
      if (aktc % (gr + 1) == 0) {
        rem_b++;
      }
      if (rem_a >= 0 && rem_b <= (rem_a + 1) * gr) {
        pref = aktc;
        kl = aktc + 1;
      } else {
        kp = aktc - 1;
      }
    }
    int x = pref / (gr + 1);
    int y = pref - x * (gr + 1);
    //int rem_b = b - x;
    int t = a - (gr * x + y);
    int z = b - x - gr * t;
    debug(a, b, gr, pref, x, y, z, t);
    assert(gr * x + y + t == a);
    assert(x + z + gr * t == b);
    string res;
    debug(a, b, c, d, gr);
//     string res;
    FOR (i, c, d) {
      if (i <= pref) {
        if (i % (gr + 1) == 0) {
          res += 'B';
        } else {
          res += 'A';
        }
      } else if (i <= pref + z) {
        res += 'B';
      } else if ((n + 1 - i) % (gr + 1) == 0) {
        res += 'A';
      } else {
        res += 'B';
      }
    }
    if (sw == 0) {
      cout<<res<<"\n";
    } else {
      reverse(ALL(res));
      for (auto& cc : res) {
        cc = 'A' + 'B' - cc;
      }
      cout<<res<<"\n";
    }
  }
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  return 0;
}


Measured memory_bytes: 384