单项选择题
When approaching a preferred-channel buoy，the best channel is NOT indicated by the（）.
A.light characteristic B.color of the uppermost band C.shape of an unlighted buoy D.color of the light
单项选择题 When a buoy marks a channel bifurcation，the preferred channel is NOT indicated by（）.
单项选择题 What is the major advantage of high altitude observations?（）
单项选择题 What is the light characteristic of a lighted，preferred-channel buoy? （）
