单项选择题
A.between ship stations and shore-based communication networks B.concern the management and operation of ships C.may have an impact of the safety on ships D.all of A, B, C
What’s the advantage when using the satellites?（）A.The ...
单项选择题What’s the advantage when using the satellites?（）
A.The message can be directed to the desired location B.The message can follow the earth‟s curvature C.The quality of message can not be affected by climatic D.the range of the message extend and the quality of reception is improved
Some radio waves（）the surface of the earth because of i...
单项选择题Some radio waves（）the surface of the earth because of its（）.
A.are capable of following / distance B.can follow / altitude C.can hardly follow / shape D.are unable following / angle
Ships equipped with Inmarsat SES send distress alerts b...
单项选择题Ships equipped with Inmarsat SES send distress alerts both（）.
A.quick and good B.convenient and certain C.easily and simply D.important and difficult
