单项选择题
Charts showing the coast of Mexico are produced by the United States（）.
A.National Geospatial-Intelligence Agency B.Coast Guard C.Naval Observatory D.National Ocean Service
单项选择题 A chart with a scale of 1:80，000 would fall into the category of a（）.
单项选择题 A chart projection depicting the poles and a small area on either side of a connecting meridian，that is sometimes used for star charts，is the（）.
单项选择题 A chart position enclosed by a square is a（n）（）.
