单项选择题
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
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相关考题
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单项选择题
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 -
单项选择题
The hydraulic oil most likely to thin out when hot and thick when cold would have a viscosity index of（）
A.20
B.40
C.60
D.80 -
单项选择题
When the steering wheel is turned, oil is directed to the steering gear rams by（）
A.modulating the oil flow with the six-way valve
B.moving the automatic pressure differential valve
C.moving the receiving telemotor which regulates the tow-way valve
D.varying the eccentricity of a floating ting or angle of a tilting box
