掌握异阶导函数：解析与应用技巧母亲动漫1~6全集动漫在线观看

　　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.