So teacher I just finished my quiz and it was OK is not bad and is not good, it was just OK.  So I have few questions to ask you. Before I ask you the question I need to show you the ex, When I was at the park yesterday, I saw a dog playing with (a / an / the) ball. I chose the answer is ( The ), but I don't understand why you can't chose ( the) , I thought they said I saw a dog playing with the ball. Can you tell me why I can't use (the)? And I think that's all for grammar 29-3.