单项选择题
The （） is used to measure the volume of a liquid or gas through a pipeline within any given period of time.
A.flowmeter B.viscometer C.micrometer D.feeler
单项选择题 Sacrificial zinc anodes are used on the saltwater side of diesel engine heat exchangers to（）.
单项选择题 With a （） load the voltage and current are in phase.
单项选择题 The star-delta starter is an effective method of （） voltage starting of a motor.
