The man to whom we handed the forms pointed out that they had not been ______ filled in. [ ]

A. slightly

B. properly

C. regularly

D. eventually

产生谐振过电压的原因是（）。

A、雷电波侵入；

B、电网参数变化；

C、电压互感器铁芯不饱和；

D、操作引起。