1. B: What did you do yesterday?

 G: I cooked dinner at home.

2. B: My mother was a teacher four years ago.

 G: Did she teach Chinese?

 B: No, she taught English.

3. G: Is your father a writer?

 B: No, he isn’t. He’s a doctor.

4. B: Was she a teacher two years ago?

   G: No, she wasn’t. She was a dancer then.