单项选择题
A.glare from background lighting B.existing visibility conditions C.elevation of the light D.observer's height of eye
Restricted areas at locks and dams are indicated by（）.A...
单项选择题Restricted areas at locks and dams are indicated by（）.
A.flashing red lights upstream and fixed red lights downstream B.yellow unlighted buoys C.signs and/or flashing red lights D.red daymarks upstream and green daymarks downstream
Preferred channel buoys indicate the preferred channel ...
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
Lighted white and orange buoys must show which color li...
单项选择题Lighted white and orange buoys must show which color light?（）
A.Orange B.White C.Red D.Alternating yellow and white
