单选题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.AcontractionBretractionCexpansionDshrinkage
单选题
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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