單項(xiàng)選擇題

"gauge pressure" means（）.

A."vacuum"
B."the excess of pressure above atmosphere"
C."figure on a gauge"
D.Any of the above

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單項(xiàng)選擇題

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

單項(xiàng)選擇題

Sacrificial zinc anodes are used on the saltwater side of diesel engine heat exchangers to（）.

A.reduce electrolytic action on heat exchanger metals
B.keep heat transfer surfaces shiny and clean
C.prevent rapid accumulation of marine growth
D.provide a protective coating on heat exchanger surfaces