单项选择题
A.Proceed on present course and speed since the vessel is stopped and making no way through the water
B.Keep clear of the vessel because it has a diver down
C.Attempt to call the vessel on VHF radiotelephone because someone on board requires medical assistance
D.Approach with caution because the vessel is a fishing vessel and its nets are fouled on an obstruction
单项选择题 As defined in the Rules，a towing light is a yellow light having the same characteristics as a(n)（）.
单项选择题 Approaching an anchorage in fog，you hear one short，one prolonged，and one short blast in that sequence on a ship’s whistle． This indicates（）.
单项选择题 An occulting light is one in which（）.