单项选择题 A parallel-plate capacitorwith area A and separation d is filled with a dielectric medium of relative permittivity  (dielectric constant). The capacitor is being charged at a constant rate dV/dt. Here V is the potential difference between the two plates of the capacitor. The displacement current between the plates is            . A、 B、 C、 D、

单项选择题

单项选择题 （    ）一般设置在入口处附近，以别出心裁的设计吸引顾客，切忌平面化；也可以通过一些生活化场景使顾客感到亲切自然，进而产生共鸣。 A. 橱窗 B. 展示区 C. 收银台