单项选择题
Geostationary satellite are artificial satellite which（）.
A.always move slowly B.are in one place only C.sometimes move and sometime don‟t D.synchronize with the movement of the earth
单项选择题 A radio link between a transmitting earth station and a receiving earth station through one satellite is named a（）.
单项选择题 International Navtex service is（）.
单项选择题 What language does International NAVTEX use?（）
