单项选择题
On a chart，the characteristic of the light on a lighthouse is shown as flashing white with a red sector.The red sector（）.
A.Indicates the limits of the navigable channel B.Indicates a danger area C.Is used to identify the characteristics of the light D.Serves no significant purpose
单项选择题 In very high latitudes，the most practical chart projection is the（）.
单项选择题 How would you pass a red buoy in the maritime buoyage system“A” （）.
单项选择题 Depiction of TSS's on charts uses（）as the primary color.
