听下面一段材料,回答第1至3题。 1. What's the relationship between the two speakers? [ ] A. Doctor and driver. B. Driver and passenger. C. Policeman and witness. 2. What caused the accident to happen? [ ] A. A black dog. B. A black car. C. A white car. 3. When did the ambulance come according to the conversation? [ ] A. At about 8:30. B. At about 8:45. C. At about 9:00.