单项选择题
A.used at the earliest opportunity
B.hydro-tested
C.recharged
D.weighed again in one month
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 with a natural scale of 1:160，000 is classified as 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（）.