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單項(xiàng)選擇題

The single acting cylinder is the simplest form where pressure is applied to the full area of the piston head to move the load through piston rod extensionThe load causes rod （） when the drive pressure is released.

A.contraction
B.retraction
C.expansion
D.shrinkage

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單項(xiàng)選擇題

Among the basic categories of equipment, which of the following are used to convert the hydraulic energy into linear motion?（）

A.Hydraulic pumps
B.Valves
C.Hydraulic cylinders
D.Hydraulic motors

單項(xiàng)選擇題

In a general cargo crane, （） is fitted to raise or lower the jib.

A.the slewing motor
B.the luffing motor
C.the hoisting motor
D.none of the above