单项选择题
When must the Master or person in charge of a ship log the position of load line marks in relation to the surface of the water in the logbook?（）
A.Once a day B.At the change of every watch C.Only when in fresh or brackish water D.Prior to getting underway
单项选择题 What is the purpose of the limit switch on gravity davits?（）
单项选择题 What is the most important difference between the bow type anchor shackle and the D-type anchor shackle? （）
单项选择题 What is the function of an air receiver in the compressed air system on a ship? （）
