单项选择题
What area of the earth cannot be shown on a standard Mercator chart（）.
A.Equator B.Areas including both North and South latitudes C.North and South Poles D.A narrow band along the central meridian
单项选择题 Traffic separation schemes adopted by the IMO are listed in（）.
单项选择题 The time required for a lighted aid to complete a full cycle of light changes is listed in the Light List as the（）.
单项选择题 The recording fathometer produces a graphic record of the（）.
