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單項(xiàng)選擇題

A viscosity regulator used for an engine is usually provided in order to （） for an engine burning heavy fuel oil.

A.regulate the fuel supply
B.maintain a constant fuel viscosity at the fuel valves
C.maintain efficient cooling
D.alter the fuel density

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單項(xiàng)選擇題

A manometer is used to measure （）.

A.pressure
B.temperature
C.volume
D.specific gravity

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