单项选择题
A.Free of charge B.Important C.Required D.Unnecessary
Mariners should ensure correct（）of aids to navigation d...
单项选择题Mariners should ensure correct（）of aids to navigation during twilight periods when some lighted aids to navigation are lit while others are not.
A.identification B.distinction C.discrimination D.clearly seeing
If the winch should fail while you are hauling in the a...
单项选择题If the winch should fail while you are hauling in the anchor，what prevents the anchor cable from running out（）.
A.Chain stopper B.Devil's claw C.Hawse ratchet D.Riding pawl
If the ship is alongside the wharf，what kind of（）is use...
单项选择题If the ship is alongside the wharf，what kind of（）is used?
A.pilot ladder B.rope ladder C.rod ladder D.accommodation ladder
