单项选择题
（） operates at a transfer rate of up to 9600 bits per second and is telephone，telex and facsimile（fax）capable.
A.INMARSAT A B.INMARSAT C C.SafetyNET D.NAVTEX
单项选择题 （） is not required by bridge-to-bridge communications.
单项选择题 （）is an area within the radiotelephone coverage of at least one VHF coast station in which continuous Digital Selective Calling is available.
单项选择题 What is the basic concept of GMDSS? （）
