#include <bits/stdc++.h>

//    #include <boost/multiprecision/cpp_int.hpp>
 #define int long long
 #define inf  1000000007
 #define pa pair<int,int>
 #define ll long long
 #define pal pair<double,double>
 #define ppap pair<pa,int>
  #define PI 3.14159265358979323846
  #define paa pair<int,char>
  #define  mp make_pair
  #define  pb push_back
  #define EPS (1e-10)
                                          
    int dx[8]={0,1,0,-1,1,1,-1,-1};
    int dy[8]={1,0,-1,0,-1,1,1,-1};
                                            using namespace std;
                                   			class pa3{
                                            	public:
                                            	int x;
                                   				int y,z;
                                            	pa3(int x=0,int y=0,int z=0):x(x),y(y),z(z) {}
                                            	bool operator < (const pa3 &p) const{
                                            		if(x!=p.x) return x<p.x;
                                            		if(y!=p.y) return y<p.y;
                                            		 return z<p.z;
                                            		//return x != p.x ? x<p.x: y<p.y;
                                            	}
                                   				bool operator > (const pa3 &p) const{
                                            		if(x!=p.x) return x>p.x;
                                            		if(y!=p.y) return y>p.y;
                                            		 return z>p.z;
                                            		//return x != p.x ? x<p.x: y<p.y;
                                            	}
                                            	bool operator == (const pa3 &p) const{
                                            		return x==p.x && y==p.y && z==p.z;
                                            	}
                                            		bool operator != (const pa3 &p) const{
                                            			return !( x==p.x && y==p.y && z==p.z);
                                            	}
                                            
                                            };
                                            
                                            class pa4{
                                            	public:
                                            	int x;
                                            	int y,z,w;
                                            	pa4(int x=0,int y=0,int z=0,int w=0):x(x),y(y),z(z),w(w) {}
                                            	bool operator < (const pa4 &p) const{
                                            		if(x!=p.x) return x<p.x;
                                            		if(y!=p.y) return y<p.y;
                                            		if(z!=p.z)return z<p.z;
                                            		return w<p.w;
                                            		//return x != p.x ? x<p.x: y<p.y;
                                            	}
                                            	bool operator > (const pa4 &p) const{
                                            		if(x!=p.x) return x>p.x;
                                            		if(y!=p.y) return y>p.y;
                                            		if(z!=p.z)return z>p.z;
                                            		return w>p.w;
                                            		//return x != p.x ? x<p.x: y<p.y;
                                            	}
                                            	bool operator == (const pa4 &p) const{
                                            		return x==p.x && y==p.y && z==p.z &&w==p.w;
                                            	}
                                            		
                                            
                                            };
                                            class pa2{
                                            	public:
                                            	int x,y;
                                            	pa2(int x=0,int y=0):x(x),y(y) {}
                                            	pa2 operator + (pa2 p) {return pa2(x+p.x,y+p.y);}
                                            	pa2 operator - (pa2 p) {return pa2(x-p.x,y-p.y);}
                                            	bool operator < (const pa2 &p) const{
                                            		return y != p.y ? y<p.y: x<p.x;
                                            	}
                                            	bool operator > (const pa2 &p) const{
                                            		return x != p.x ? x<p.x: y<p.y;
                                            	}
                                            	bool operator == (const pa2 &p) const{
                                            		return abs(x-p.x)==0 && abs(y-p.y)==0;
                                            	}
                                            	bool operator != (const pa2 &p) const{
                                            		return !(abs(x-p.x)==0 && abs(y-p.y)==0);
                                            	}
                                            		
                                            
                                            };
                                        

                                            class Point{
                                            	public:
                                            	double x,y;
                                            	Point(double x=0,double y=0):x(x),y(y) {}
                                            	Point operator + (Point p) {return Point(x+p.x,y+p.y);}
                                            	Point operator - (Point p) {return Point(x-p.x,y-p.y);}
                                            	Point operator * (double a) {return Point(x*a,y*a);}
                                            	Point operator / (double a) {return Point(x/a,y/a);}
                                            	double absv() {return sqrt(norm());}
                                            	double norm() {return x*x+y*y;}
                                            	bool operator < (const Point &p) const{
                                            		return x != p.x ? x<p.x: y<p.y;
                                            	}
                                            	bool operator == (const Point &p) const{
                                            		return fabs(x-p.x)<EPS && fabs(y-p.y)<EPS;
                                            	}
                                            };
                                            typedef Point Vector;
                                     #define pl pair<int,pas>
                                            struct Segment{
                                            Point p1,p2;
                                            };
                                             double dot(Vector a,Vector b){
                                            	return a.x*b.x+a.y*b.y;
                                            }
                                            double cross(Vector a,Vector b){
                                            	return a.x*b.y-a.y*b.x;
                                            }
                                        
                bool parareru(Point a,Point b,Point c,Point d){
                //	if(abs(cross(a-b,d-c))<EPS)cout<<"dd "<<cross(a-b,d-c)<<endl;
                	return abs(cross(a-b,d-c))<EPS;
                }
                double distance_ls_p(Point a, Point b, Point c) {
                  if ( dot(b-a, c-a) < EPS ) return (c-a).absv();
                  if ( dot(a-b, c-b) < EPS ) return (c-b).absv();
                  return abs(cross(b-a, c-a)) / (b-a).absv();
                }
                bool is_intersected_ls(Segment a,Segment b) {
                	if(a.p1==b.p1||a.p2==b.p1||a.p1==b.p2||a.p2==b.p2) return false;
                	if(parareru((a.p2),(a.p1),(a.p1),(b.p2))&&parareru((a.p2),(a.p1),(a.p1),(b.p1))){
                //		cout<<"sss"<<endl;
                		if(dot(a.p1-b.p1,a.p1-b.p2)<EPS) return true;
                		if(dot(a.p2-b.p1,a.p2-b.p2)<EPS) return true;
                		if(dot(a.p1-b.p1,a.p2-b.p1)<EPS) return true;
                		if(dot(a.p1-b.p2,a.p2-b.p2)<EPS) return true;
                		return false;
                	}
                  else return ( cross(a.p2-a.p1, b.p1-a.p1) * cross(a.p2-a.p1, b.p2-a.p1) < EPS ) && ( cross(b.p2-b.p1, a.p1-b.p1) * cross(b.p2-b.p1, a.p2-b.p1) < EPS );
                }
                 
                double segment_dis(Segment a,Segment b){
                	if(is_intersected_ls(a,b))return 0;
                	double r=distance_ls_p(a.p1, a.p2, b.p1);
                	r=min(r,distance_ls_p(a.p1, a.p2, b.p2));
                	r=min(r,distance_ls_p(b.p1, b.p2, a.p2));
                	r=min(r,distance_ls_p(b.p1, b.p2, a.p1));
                	return r;
                }
                Point intersection_ls(Segment a, Segment b) {
                  Point ba = b.p2-b.p1;
                  double d1 = abs(cross(ba, a.p1-b.p1));
                  double d2 = abs(cross(ba, a.p2-b.p1));
                  double t = d1 / (d1 + d2);
                 
                  return a.p1 + (a.p2-a.p1) * t;
                }
                
                                string itos( int i ) {
                                ostringstream s ;
                                s << i ;
                                return s.str() ;
                                }
                                 
                                int gcd(int v,int b){
                                	if(v>b) return gcd(b,v);
                                	if(v==b) return b;
                                	if(b%v==0) return v;
                                	return gcd(v,b%v);
                                }
                 
                                double distans(double x1,double y1,double x2,double y2){
                                	double rr=(x1-x2)*(x1-x2)+(y1-y2)*(y1-y2);
                                	return sqrt(rr);
                                	
                                }
                                int mod;
ll extgcd(ll a, ll b, ll &x, ll &y) {
    if (b == 0ll) {
        x = 1ll;
        y = 0ll;
        return a;
    }
    ll d = extgcd(b, a%b, y, x);
    y -= a/b * x;
    return d;
}
pa operator+(const pa & l,const pa & r) {   
    return {l.first+r.first,l.second+r.second};                                    
}    
pa operator-(const pa & l,const pa & r) {   
    return {l.first-r.first,l.second-r.second};                                    
} 
                                
                int pr[1200010];
                int inv[1200010];
                
                int beki(int wa,int rr,int warukazu){
                	if(rr==0) return 1%warukazu;
                	if(rr==1) return wa%warukazu;
                	wa%=warukazu;
                	if(rr%2==1) return ((ll)beki(wa,rr-1,warukazu)*(ll)wa)%warukazu;
                	ll zx=beki(wa,rr/2,warukazu);
                	return (zx*zx)%warukazu;
                }
    double bekid(double w,int r){
    	if(r==0) return 1.0;
    	if(r==1) return w;
    	if(r%2) return bekid(w,r-1)*w;
    	double f=bekid(w,r/2);
    	return f*f;
    }
                
    			int comb(int nn,int rr){
    				int r=pr[nn]*inv[rr];
    				r%=mod;
    				r*=inv[nn-rr];
    				r%=mod;
    				return r;
    			}
                
                void gya(int ert){
                	pr[0]=1;
                	for(int i=1;i<=ert;i++){
                		pr[i]=(pr[i-1]*i)%mod;
                	}
                	for(int i=0;i<=ert;i++) inv[i]=beki(pr[i],mod-2,mod);
                	
                }
                
              //   cin.tie(0);
    		//	ios::sync_with_stdio(false);
    			//priority_queue<pa3,vector<pa3>,greater<pa3>> pq;            
                 //sort(ve.begin(),ve.end(),greater<int>());
    //mt19937(clock_per_sec);
  //  mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count()) ;
	   
       
                               //----------------kokomade tenpure------------



string solve_gu(int a,int b){
	vector<int>ve;
	for(int i=0;i<a;i++)ve.pb(0);
	for(int i=0;i<b;i++)ve.pb(1);
	
	
	pair<int,vector<int>> g;
	g.first=inf;
	
	do{
		int ma=1;
		int len=1;
		for(int i=0;i<a+b;i++){
			if(i){
				if(ve[i-1]!=ve[i]){
					ma=max(ma,len);
					len=1;
				}
				else len++;
				if(len>g.first)goto lll;
			}
			
		}
		ma=max(ma,len);
		
		g=min(g,mp(ma,ve));
		lll:;
		
	}while(next_permutation(ve.begin(),ve.end()));
	string st="";
	for(auto c:g.second)st+=(c?"1":"0");
	return st;
}


string solve(int a,int b,int c,int d){
	assert(a>=b);
//	cout<<a<<" "<<b<<" "<<c<<" "<<d<<endl;
	string ans="";
	//assert(a<=1010 && b<=1010);
	if(a==b){
		for(int i=c;i<d;i++){
			if(i%2)ans+="1";
			else ans+="0";
		}
		return ans;
	}
	
	if(a==b+1){
		for(int i=c;i<d;i++){
			if(i%2)ans+="1";
			else ans+="0";
		}
		return ans;
	}
	
	
		int x=(a/(b+1)+!!(a%(b+1)));
		
	//	int aa=(b+1)*(a/(b+1)+!!(a%(b+1)));
		
		//cout<<x<<" "<<aa<<endl;
		
		
	if(a>=x*b){
		for(int i=c;i<d;i++){
			if(i%(x+1)==x)ans+="1";
			else ans+="0";
		}
		return ans;
	}
	/*
	int nokori=x*b-a;
	string tani="";
	for(int i=0;i<x;i++)tani+="0";
	tani+="1";
	string s="";
	for(int i=0;i<b;i++)s+=tani;
	
	vector<int> ve;
	assert(s.length()==b*(x+1));
	ve.resize((int)s.length(),0);
	for(int i=0;i<b*(x+1);i++){
		if(s[i]=='1')ve[i]=1;
	}
	int cnt=1;
	for(int ima=b*(x);ima>=0;ima-=x+1){
		if(cnt%x==0)ve[ima]=1;
		cnt++;
	}
	for(int i=b*(x+1)-1;;i--)if(ve[i]==0){
		ve[i]=-1;
		nokori--;
		if(nokori==0) break;
	}
	cnt=0;
	for(int i=0;;i++)if(ve[i]>=0){
		if(c<=cnt && cnt<d){
			ans+=s[i];
			if(cnt==d-1)break;
		}
			cnt++;
	
	}
	*/
	//cout<<a<<" "<<b<<" "<<c<<" "<<d<<endl;
	swap(c,d);
	c=a+b-c;
	d=a+b-d;
//	cout<<c<<" "<<d<<endl;
	int nokori=x*b-a;
//	cout<<nokori<<endl;
	int d1=nokori/(x*x-1);
	// di 1--(x)個--10
	// (x+1)*d1文字
//	cout<<"d1 "<<d1<<endl;
	nokori%=x*x-1;
	int d2=nokori/x;
	// d2は長さ 1----1
	// d2文字
//	cout<<"d2 "<<d2<<endl;
	nokori%=x;
	
	int d3=x-nokori;
//	cout<<"d3 "<<d3<<endl;
	
	// 10-(d3)-0
	// d3+1文字
	
	for(int i=c;i<d;i++){
		if((x+1)*d1>i){
			int ii=i%(x+1);
			if(ii==x)ans+="0";
			else ans+="1";
		}
		else if((x+1)*d1+d2>i){
			ans+="1";
		}
		else if((x+1)*d1+d2+d3+1>i){
			if(i==(x+1)*d1+d2)ans+="1";
			else ans+="0";
		}
		else {
			int ii=i-((x+1)*d1+d2+d3+1);
			ii%=x+1;
			if(ii==0)ans+="1";
			else ans+="0";
		}
	}
	
	//cout<<ans<<endl;
	
	reverse(ans.begin(),ans.end());
	return ans;
}

signed main(){

			  cin.tie(0);
   			ios::sync_with_stdio(false);
//	cout<<solve_gu(8,10)<<endl;
//	cout<<solve_gu(10,8)<<endl;
//	return 0;
//	cout<<solve(6,3,0,9)<<endl;
//	for(int i=10;i<=60;i++)cout<<solve(i,10,0,10+i)<<endl;
//	return 0;
int q;
	cin>>q;
	for(int i=0;i<q;i++){
		int a,b,c,d;
		cin>>a>>b>>c>>d;
		c--;
		
		string s;
		if(a>=b){
			s=solve(a,b,c,d);
			for(auto c:s){
			if(c=='0')cout<<'A';
			else cout<<'B';
		}
		}
		else{
			s=solve(b,a,a+b-d,a+b-c);
			reverse(s.begin(),s.end());
			for(auto c:s){
			if(c=='1')cout<<'A';
			else cout<<'B';
		}
		}
		
		cout<<"\n";
	}
	return 0;
}

Measured memory_bytes: 384