单项选择题
Which system(s) in the hydraulic systems of crane always hold(s) single side of load?（）
A.hoisting system only
B.hoisting system and luffing system
C.hoisting system and slew and slewing system
D.slewing system only
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相关考题
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单项选择题
Crude oil washing of cargo tanks has the following advantages except for （）
A.reducing the erosion of the cargo tanks
B.increasing the total quantity of oil to carry
C.reducing the quantity of water contained in oil
D.reducing cargo discharged time -
单项选择题
Where is the cooling water from the compensating tank in the cooling water system of main engine lead to?（）
A.discharge side of the centrifugal pump
B.suction side of the centrifugal pump
C.the lowest point of the cooling water system
D.inlet of the main engine -
单项选择题
From viewpoint of practice, it is sometimes important to detect abnormal happenings in the running gear by（）
A.a keen sense of hearing
B.rich theory
C.communicating ability with others
D.repetition work
