单项选择题
A.the starboard side of the channel B.the centerline of the channel C.an obstruction where the preferred channel is to starboard D.special purpose areas
During the day，a vessel with a tow over 200 meters in l...
单项选择题During the day，a vessel with a tow over 200 meters in length will show（）.
A.a black ball B.a diamond shape C.two cones，apexes together D.one cone，apex upward
Daymarks marking the starboard side of the channel when...
单项选择题Daymarks marking the starboard side of the channel when going towards the sea are（）.
A.green squares B.green triangles C.red squares D.red triangles
By night，you sight the lights of a vessel engaged in un...
单项选择题By night，you sight the lights of a vessel engaged in underwater operations. If an obstruction exists on the port side of the vessel，it will be marked by（）.
A.a floodlight B.two red lights in a vertical line C.a single red light D.any visible lights
