单项选择题
An SES operator can chose the most suitable CESs according to（）.
A.the routing agreement for a particular ocean region B.The communication service he required C.the positions of his ship and the CESs D.B and C
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.
单项选择题 The position of the AOR-W satellite in the INMARSAT system is（）above the equator.
