单项选择题
A radio link between a transmitting earth station and a receiving earth station through one satellite is named a（）.
A.Radio link B.Space segment C.Satellite link D.upper link
单项选择题 International Navtex service is（）.
单项选择题 What language does International NAVTEX use?（）
单项选择题 When the power of SART is on, it will（）.
