There are some back-up satellites in the event of failure. If the operational satellite is out of work,（）.

单项选择题The satellites over the major ocean regions cover the globe（）.

A.besides the polar regions
B.including the North Pole and the South Pole
C.above 70N and below 70S
D.as far north and south 70

单项选择题（）is a space system using one or more artificial earth satellites.

A.satellite network
B.Satellite Link
C.INMARSAT
D.Satellite System

单项选择题The establishment of INMARSAT as an independent organization marked a great step forward for maritime radio communications. What does “marked a great step” mean in the sentence?（）

A.To run faster than ever
B.To go forward
C.To march without stopping
D.A significant symbol of a great improvement in maritime communication

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（）.

A.the weather is always terrible
B.the condition there is complicated
C.the signals are too strong
D.their SES may receive the signals from unwanted satellite

单项选择题If EGC receiver shares a same antenna with Inmarsat SES, it means that it can receive MSI（）.

A.from any Inmarsat satellite
B.from any appropriate Navtex and EGC station
C.via the satellite the SES is tracking
D.from any RCC and coast station