听下面一段材料，回答第1-4小题。 1. How many persons were there in the room when someone was knocking at the door? [     ] A. One person. B. Two persons. C. Three persons. 2. What did the young man wear? [     ] A. A white shirt. B. A pair of glasses. C. Long trousers. 3. Who was the young man? [     ] A. He was a friend of the writer's. B. He was a friend of the writer's brother's. C. He was a strange man to them. 3. What was probably the end of the story? [     ] A. The young man was taken away by the police. B. The young man became their friend. C. The young man ran away.