Ответ:
1. I'm not a pupil. I'm a student.
2. His brother is a pupil. He's at school.
3. My parents are engineers. They are at work.
4. Are you a doctor? - No, I'm a teacher.
5. Is your sister a pupil? - No, she's an engineer. She's at work.
6. Her sister isn't a secretary. She is a teacher.
7. Are they doctors? - No, they are pilots.
8. Is your sister at home? - No, she is at work.
9. Our father is a scientist.
10. His aunt isn't a doctor. She is an actress.
11. It is my book. It is on a table.
12. My cousin isn't a scientist, he is an engineer.
13. There are pictures. They are at the wall. Pictures are very beautiful.
14. My grandmother is pensioner. She is not at work. She is at home.
15. Are your children pupils? - Yes, they are pupils.