问答题 8.要求上级机关做出明确答复的文种是[填空1]。

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