单项选择题
The conventional cargo handling equipment is the union purchase.（）
A.传统的装卸货设备是双杆联吊。 B.传统的装卸货设备是重吊杆。 C.传统的装卸货设备是克令吊。 D.传统的装卸货设备是吊杆。
单项选择题 After operation, we should stop the electric motor.（）
单项选择题 High-speed operation and rough handling of covers are dangerous.（）
单项选择题 These hatch covers are usually driven by electric or hydraulic power.（）
