单项选择题
What is the light characteristic of a lighted，preferred-channel buoy? （）
A.Group flashing B.Composite group flashing C.Interrupted quick flashing D.Fixed and flashing
单项选择题 What indicates a dual purpose buoy? （）
单项选择题 What describes an accurate position that is NOT based on any prior position? （）
单项选择题 Uncharted lights，fog signals and radar beacon transmissions may be（）near the station.
