听对话，回答问题。 1. Why was Einstein standing on the bridge? A. He was thinking about a problem. B. He was talking something with his friends. C. He was waiting for a friend of his. 2. When did it begin to rain? A. After he got to the bridge. B. Before he came to the bridge. C. While he was waiting on the bridge. 3. How did Einstein know it was raining? A. His friend told him. B. His paper was wet. C. His clothes were wet. 4. Which of the followings is true? A. Scientists like thinking in the rain. B. Scientists are more careful in their studies than in their life. C. The less the scientists care about their life, the more they can study.