lichess.org/training/3431
After your third move Qg3+ and then Kh1, there is another mating sequence with Qh3+, Qh2, Qxh2# (http://en.lichess.org/ew5wgPwOA5nh) cause the bishop is pinned by the rook. Well it's not the best move, cause you could mate in one move, but it's a 'good move - but you can do better' ;)
After your third move Qg3+ and then Kh1, there is another mating sequence with Qh3+, Qh2, Qxh2# (http://en.lichess.org/ew5wgPwOA5nh) cause the bishop is pinned by the rook. Well it's not the best move, cause you could mate in one move, but it's a 'good move - but you can do better' ;)