单项选择题
Without permission of（）, a ship earth station can not enter the system.
A.ITU B.IMO C.INMARSAT ORGANIZATION D.the nearest CES
单项选择题 An SES operator can chose the most suitable CESs according to（）.
单项选择题 The NCS of INMARSAT-A system in the AOR-E is in（）.
单项选择题 Each NCS woks as a type of（）, assisting controlling and monitoring telex and telephone network as quickly as possible.
