单项选择题
Preferred channel buoys indicate the preferred channel to transit by（）.
A.odd or even numbers B.the color of their top band C.the location of the buoy in the channel junction D.the buoy's light rhythms
单项选择题 Lighted white and orange buoys must show which color light?（）
单项选择题 In plotting a running fix，how many fixed objects are needed to take your lines of position from? （）
单项选择题 At the magnetic equator there is no induced magnetism in the vertical soft iron because（）.
