作为一名值班水手,你必须懂得如何调整吊杆。()
A、A. As an officer on duty, you must know how to adjust derricks.
B、B. As a sailor on duty, you must know how to adjust derricks.
C、C. As a sailor on duty, you must know how to operate cranes.
D、D. As an officer on duty, you must know how to operate cranes.