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單項選擇題

Which of the lists forms of heat transfer, if any, is illustrated by the flow of combustion gases through a boiler?（）

A.Natural convection only
B.Forced convection only
C.Both natural convection and forced convection
D.None

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單項選擇題

Auxiliary boilers can be classified as（）

A.water-tube natural circulation boilers
B.fire-tube boilers
C.water-tube forced circulation boilers
D.all of the above

單項選擇題

When the tilting box of a variable stroke axial-piston pump is perpendicular to the pump shaft, which of the following conditions will exist?（）

A.The pistons reciprocate
B.The ‘B’ end cylinder barrel rotates
C.There is no fluid flow
D.Power is transmitted hydraulically