单项选择题
A.Natural convection only B.Forced convection only C.Both natural convection and forced convection D.None
Auxiliary boilers can be classified as（）A.water-tube na...
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
When the tilting box of a variable stroke axial-piston ...
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
The hydraulic oil most likely to thin out when hot and ...
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
