单项选择题
When entering a channel from seaward，the numbers on buoys（）.
A.are the same as their Light List number B.are marked in 6 inch figures with retroreflective material C.increase with the even numbers to starboard D.decrease with the odd numbers to starboard
单项选择题 When approaching a preferred-channel buoy，the best channel is NOT indicated by the（）.
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?（）
