— He works quite hard.

— Maybe you don't know that he always ____ without asking for leave when he ____ in another company. [ ]

A. went to work; was

B. goes to work; is

C. didn't go to work ; was

D. doesn't go to work; is

当电网接有较多高压电动机或者较多的电缆线路时，由于它们的绝缘水平较低，瞬间性的接地故障相对较少，为了保证绝缘不受损坏，为减少单相接地发展成为多重接地故障，宜采用（）系统。

A.中性点直接接地

B.中性点经电容接地

C.中性点经电阻接地

D.中性点经电感接地