单项选择题
A Mercator chart is a （）.
A.cylindrical projection B.simple conic projection C.polyconic projection D.rectangular projection
单项选择题 A revised print of a chart is made （）.
单项选择题 All straight lines represent great circle tracks on a chart based on a(n) （）.
单项选择题 Chart correction information is NOT disseminated through the （）.
