单项选择题
When a cargo boom or crane is rated at varying capacities，there will be a table at the controls which relates safe working load to（）.
A.winch speed B.boom strength C.load radius D.cable strength
单项选择题 When（）clean ballast water from any vessel，an application shall be made to Harbor Authorities for approval.
单项选择题 What would be prima facie evidence of unseaworthiness? （）
单项选择题 What is the purpose of pressure-vacuum relief valves? （）
