单项选择题 （） shall be continuously powered and shall have an automatic changeover to a stand by power supply in case of loss of normal power supply.

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.