Moon's improving vocabulary

Moon has been talking quiet a lot ever since he turned two and a half years. It was then, that he started his pre-school and ever since, there had been great improvements in his English speech as well. He surprises us with expressions like 'Oh my God, what are you doing!' or 'Mummy, I love you' or 'Mummy, i am go to toilet', yes, he pleasantly surprises us when he speaks wrong sentences as well. Never forgets to use 'thank you', 'thanks', 'sorry', 'please' relevantly. Makes excessive use of sentences like 'Mummy, i am watching cartoon', 'we are going to park', 'i am go to sleep','give me the keys, i m open the door'. Can choose a language according to the person he is talking to. I don't actually mind his wrong English sentences, after all, this is the way he started with Hindi.