异阶导函数揭示了函数变化的深层结构。重生之一世枭龙江志浩

　　In a class room, a girl is sitting on the desk, solving a math quiz. If she cannot solve it in time, a horrible thing is likely to happen. The clock is ticking but the quiz is not likely to be solved. And her mechanical pencil breaks down. However she has to solve the quiz.