单项选择题 The liquid flowing in the capillary is such that the difference in （） readings taken before the capillary and after it is related to the oil viscosity.

单项选择题 The switchboards for a-csystems differ from the d-cswitch gear in that the open type panels are generally（） and the dead-front switch gear is the common rule.

单项选择题 Electrical supply is always needed even if only for lighting so after a ship goes into service it is extremely rare for the main bus-bars to be dead, it therefore follows that the bus-bars are continuously alive（） the life of the ship.