1. Complete the sentences with a or an if necessary. a) This is Dan and this is Nicola. They are ... teachers. And this is Bob. He is not... teacher. He is ...architect. b) My father and mother are ... doctors and they work in .. .hospital. My father is ... cardiologist and my mother is ... anesthetists. I don't want to be ... doctor, i want to be... actor. And my two sisters don't want to be ... doctors. They want to be ... artists.