三块平行放置的金属板A、B、C其面积均为S，AB间距离为x，BC间距离为d，设d极小，金属板可视为无限大平面，忽略边缘效应与A板的厚度，当B、C接地(如图)，且A导体所带电荷为Q时，则B板上的感应电荷为

A、
B、
C、
D、

单项选择题One mechanic pushes a 2.50×103-kg car from rest to a speed of v, doing 5 000 J of work in the process. During this time, the car moves 25.0 m. Neglecting friction between car and road, find the horizontal force exerted on the car. ()

单项选择题A． B． C． D．