水手应该知道船上吊杆的安全工作负荷。（）

• A、Sailors should know the SWL of cranes on board their ship.
• B、Sailors should know the SWL of derricks on board their ship.
• C、Officers should know the SWL of derricks on board their ship.
• D、Officers should know the SWL of cranes on board their ship.