Решение: We start work at 9 o’clock.
1. General question: Does she start work at 9 o’clock? — Yes, she does. No, she doesn’t.
2. Alternative question: Does he start work at 9 o’clock or at 10 o’clock? — Yes, he does.
3. Special question: What time does it start work? — It starts work at 9 o’clock.
4. Disjunctive question (Tag): She starts work at 9 o’clock, doesn’t she? — Yes, she does.
5. Who-question: Who starts work at 9 o’clock? — I don’t know who starts work at 9 o’clock.