单项选择题
A.Space segment, NCC, RCC, SES and CES
B.Space Segment, a satellite system, C system, NCC and NCS
C.Space Segment, NCC, NCS,CES and SES
D.A system, C system, satellite system, earth stations and NCS
单项选择题 The INMARSAT consists of（）major components.
单项选择题 why should the SES operators be very careful when the ship enters the area where three ocean regions overlap? Because（）.
单项选择题 The quality of EGC messages is（）affected by the position of the ship, the time of reception and climatic conditions.