/*{{{*/
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<string>
#include<iostream>
#include<sstream>
#include<set>
#include<map>
#include<queue>
#include<bitset>
#include<vector>
#include<limits.h>
#include<assert.h>
#define SZ(X) ((int)(X).size())
#define ALL(X) (X).begin(), (X).end()
#define REP(I, N) for (int I = 0; I < (N); ++I)
#define REPP(I, A, B) for (int I = (A); I < (B); ++I)
#define FOR(I, A, B) for (int I = (A); I <= (B); ++I)
#define FORS(I, S) for (int I = 0; S[I]; ++I)
#define RS(X) scanf("%s", (X))
#define SORT_UNIQUE(c) (sort(c.begin(),c.end()), c.resize(distance(c.begin(),unique(c.begin(),c.end()))))
#define GET_POS(c,x) (lower_bound(c.begin(),c.end(),x)-c.begin())
#define CASET int ___T; scanf("%d", &___T); for(int cs=1;cs<=___T;cs++)
#define MP make_pair
#define PB push_back
#define MS0(X) memset((X), 0, sizeof((X)))
#define MS1(X) memset((X), -1, sizeof((X)))
#define LEN(X) strlen(X)
#define F first
#define S second
using namespace std;
typedef int64_t LL;
typedef uint64_t ULL;
typedef long double LD;
typedef pair<int,int> PII;
typedef vector<int> VI;
typedef vector<LL> VL;
typedef vector<PII> VPII;
typedef pair<LL,LL> PLL;
typedef vector<PLL> VPLL;
template<class T> void _R(T &x) { cin >> x; }
void _R(int &x) { scanf("%d", &x); }
void _R(int64_t &x) { scanf("%lld", &x); }
void _R(double &x) { scanf("%lf", &x); }
void _R(char &x) { scanf(" %c", &x); }
void _R(char *x) { scanf("%s", x); }
void R() {}
template<class T, class... U> void R(T &head, U &... tail) { _R(head); R(tail...); }
template<class T> void _W(const T &x) { cout << x; }
void _W(const int &x) { printf("%d", x); }
void _W(const int64_t &x) { printf("%lld", x); }
void _W(const double &x) { printf("%.16f", x); }
void _W(const char &x) { putchar(x); }
void _W(const char *x) { printf("%s", x); }
template<class T,class U> void _W(const pair<T,U> &x) {_W(x.F); putchar(' '); _W(x.S);}
template<class T> void _W(const vector<T> &x) { for (auto i = x.begin(); i != x.end(); _W(*i++)) if (i != x.cbegin()) putchar(' '); }
void W() {}
template<class T, class... U> void W(const T &head, const U &... tail) { _W(head); putchar(sizeof...(tail) ? ' ' : '\n'); W(tail...); }
template<class T, class... U> void DEBUG(const T &head, const U &... tail) { 
#ifdef HOME
    _W('#'); _W(head); putchar(sizeof...(tail) ? ' ' : '\n'); W(tail...);
#endif
}
int MOD = 1e9+7;
void ADD(LL& x,LL v){x=(x+v)%MOD;if(x<0)x+=MOD;}
/*}}}*/
const int SIZE = 1e6+10;
int get_mi(int A,int B){
    if(A>B)swap(A,B);
    return max(1,(B+A)/(A+1));
}
int get_mi(int A_num,int A,int B,int mi){
    if(A_num>mi)return A_num;
    if(!A)return max(A_num,B);
    if(A<=B){
        return max(1,(B+A)/(A+1));
    }
    if(A+A_num<=(B+1)*mi)return mi;
    return mi+1;
}
string solve(VI input){
    int A=input[0];
    int B=input[1];
    int C=input[2];
    int D=input[3];
    int mi=get_mi(A,B);
    int ll=0,rr=A;
    while(ll<rr){
        int mm=(ll+rr+1)/2;
        int r=(mm-1)/mi;
        if(r<=B&&get_mi(mm-r*mi,A-mm,B-r,mi)<=mi)ll=mm;
        else rr=mm-1;
    }
    int lenL=ll+(ll-1)/mi;
    string res="";
    FOR(i,C,min(D,lenL)){
        if(i%(mi+1)==0)res+="B";
        else res+="A";
    }
    FOR(i,max(C,lenL+1),D){
        if((A+B+1-i)%(mi+1)==0)res+="A";
        else res+="B";
    }
    return res;
}
int main(){
    int Q;
    R(Q);
    REP(cs,Q){
        VI d;
        REP(i,4){
            int x;R(x);
            d.PB(x);
        }
        W(solve(d));
    }
    return 0;
}


Measured memory_bytes: 384