单项选择题
A. the open valve B. the stop valve C. the steam valve D. the close valve
To ensure the safety in operating hatch covers, oil the...
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
During operation, the （）should check the working condit...
单项选择题During operation, the （）should check the working condition of the derrick.
A.foreman B.operator C.opener D.stevedore
（）has more than ten percent broken wires. Stop using it...
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
