验电器在电学中主要是用来[ ]

A．测电流

B．测电压

C．测电荷量多少

D．检验物体是否带电

After you have thrown the liferaft and stowage container into the water，you inflate the liferaft by（）.

A.pulling on the painter line

B.forcing open the container which operates the CO₂

C.hitting the hydrostatic release

D.using the hand pump provided