在十字路口，尽管人多车杂，但由于行人车辆各行其道，红灯停绿灯行，穿梭有序道路也就畅通无阻。这一现象告诉我们 [ ]

A、人们要遵循道德行为规范

B、社会生活离不开规则

C、时时处处要遵守交通规则

D、遇事要谦让礼让

— Why did you step on my foot?

— I am terribly sorry. I ____ it. [ ]

A. am not noticing

B. didn't notice

C. don't notice

D. haven't noticed