第一节从方框中选出最佳选项完成下面的对话。
A: Hi, Bill. You were not at school yesterday.     
B: Oh, I fell off my bike on my way to school and hurt my leg.
A: I’m sorry to hear that.     
B: No, my father took me to the hospital.     
A: We should be more careful when we ride. In fact, we should never ride too fast.
B: You are right.         If we break the rules, we may be in danger.
A: Let’s go to the traffic station to learn more rules.
B: