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單項(xiàng)選擇題

Which of the following statements concerning fire-tube boilers is correct?（）

A.Combustion gases flow through the tubes
B.Flames impinge on the tubes
C.Combustion occurs in the tubes
D.Water flows through the tubes

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單項(xiàng)選擇題

A diesel engine cooling water system with a pH factor of 30 indicates a condition of （）.

A.slight acidity
B.slight alkalinity
C.excessive alkalinity
D.excessive acidity

單項(xiàng)選擇題

Fuel injectors used in heavy fuel oil systems are usually provided with cooling to reduce（）.

A.cold corrosion of the nozzles
B.fuel viscosity for better atomization
C.carbon accumulation on the nozzles
D.fuel detonation in the cylinders

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