1) I. Teacher: "okay guys, look at the picture, what is the item drawn on the picture called"? Pupils: "this is a house"? - 'A' is used to name a non-particular object. II. Do you remember I was talking to you about the house I liked? - 'the' is used to talk about a specific house everyone knows about. 2) I. Because your old bag has got ripped you can have a new bag. - Any bag can be bought. II. I've bought a bag, if you like it you can have the new bag to yourself. - One person can have that specific bag another person has already bought 3) сразу два в одно запишу "Customer: Hello, may I have an English dictionary please? Seller: of course, we've got the best dictionary in stock at the moment, it's called 'the English dictionary', would you like to buy it?" - the customer came to a shop to buy any dictionary (that's why 'a' was used) but the sales assistant recommended a specific dictionary that is called "the English dictionary". 4) I. Jane bought a famous picture for her dad (надеюсь изменять немного предложение можно) - she bought a picture but the reader doesn't know which one exactly, just knows that it's famous. II. This is the famous picture everyone is talking about on the internet nowadays. - the is used because we are talking about a specific picture everyone knows. 5) I. You had a copy of my report, didn't you? - 'a' article implies that many copies have been made and the person is talking about one of the copies. II. You had the copy of my report, I need it back soon. - 'the' implies that there has only been one copy made. 6) I. Josh has a sister and she is a doctor. - when talking about a profession 'a' article is used. II. "Can you see that woman? She is the doctor we've come to see." - talking about a specific doctor