单项选择题
DSC distress acknowledgements are normally transmitted by（）in respond to a receiver DSC distress call.
A.Ship stations B.Coast stations C.NCSs D.NCC
单项选择题 Distress and safety communications following DSC calling will be performed by radiotelephony or（）.
单项选择题 If a ship station relays a DSC distress call to an appropriate coast station, it means that（）.
单项选择题 After has permit the commissioning, the（）will permit the SES access to system.
