操作完后，关掉电动机。（）

单项选择题为了避免震动，用低速控制钮减低移动舱盖的速度。（）

A. To avoid shock, reduce the speed of moving hatch cover by inching control.
B. To avoid shock, reduce the speed of moving hatch cover by control levers.
C. To avoid shock, reduce the position of moving hatch cover by inching control.
D. To avoid shock, reduce the course of moving hatch cover by control levers.

单项选择题高速和野蛮操作舱盖均是危险的。（）

A. High-speed operation and rough handling of hatches are dangerous.
B. Low-speed operation and rough handling of hatches are dangerous.
C. Low-speed operation and rough handling of hatch covers are dangerous.
D. High-speed operation and rough handling of hatch covers are dangerous.

单项选择题我们每航次拆卸一次吊杆。（）

A. We dismantle the jumbo boom twice a voyage.
B. We dismantle the derricks once a voyage.
C. We examine the derricks once a voyage.
D. We dismantle the heavy derricks once a voyage.

单项选择题每一个舱盖由两个或更多的盖板组成。（）

A. Each hatch consists of two panels.
B. Each hatch cover consists of two panels.
C. Each hatch consists of two or more panels.
D. Each hatch cover consists of two or more panels.

单项选择题这些舱盖通常是用电力或液压驱动的。（）

A. These hatches are usually driven by electric or hydraulic power.
B. These hatch covers are usually driven by electric or hydraulic power.
C. These hatch covers are usually driven by electric.
D. These hatch covers are usually driven by hydraulic power.