单项选择题
A.forward error correction B.aftward error correction C.DGPS D.error-free and low error reception
How long must the GMDSS radio log be retained on board（...
单项选择题How long must the GMDSS radio log be retained on board（）.
A.At least two years after the last entry B.At least one year after the last entry C.At least 90 days after the last entry D.At least 30 days after the last entry
Each satellite broadcasts（）traffic on a designated chan...
单项选择题Each satellite broadcasts（）traffic on a designated channel.
A.LES B.ESA C.NCS D.EGC
At sea，all required GMDSS equipment（other than survival...
单项选择题At sea，all required GMDSS equipment（other than survival craft equipment）must be proven operational by（）.
A.daily testing B.either A or C C.operational use of the equipment D.testing at least every 48 hours
