单项选择题
Each satellite broadcasts（）traffic on a designated channel.
A.LES B.ESA C.NCS D.EGC
单项选择题 At sea，all required GMDSS equipment（other than survival craft equipment）must be proven operational by（）.
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.
单项选择题 （） is not required by bridge-to-bridge communications.
