单项选择题
If the hatch cover does not move, （）should be checked.
A. the open valve
B. the stop valve
C. the steam valve
D. the close valve
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相关考题
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单项选择题
To ensure the safety in operating hatch covers, oil the moving parts （）.
A. monthly
B. every three months
C. once monthly
D. every two months -
单项选择题
During operation, the （）should check the working condition of the derrick.
A.foreman
B.operator
C.opener
D.stevedore -
单项选择题
（）has more than ten percent broken wires. Stop using it at once.
A. The cargo runner
B. The cargo block
C. The derrick sling
D. The lashing wire
