单项选择题
A. When the derrick is stopped, the guy must be stowed. B. When the derrick is stopped, the guy must be topped. C. When the derrick is stopped, the guy must be lowered. D. When the guy is stopped, the derrick must be stowed.
A. As an officer on duty, you must know how to adjust derricks. B. As a sailor on duty, you must know how to adjust derricks. C. As a sailor on duty, you must know how to operate cranes. D. As an officer on duty, you must know how to operate cranes.
A. Many ships have two derricks at each hatch. B. Many ships have two winches at each hatch. C. Many ships have two derricks and two winches at each hatch. D. Many ships have two derricks and two winches at each hatch cover.