单项选择题
Distress and safety communications following DSC calling will be performed by radiotelephony or（）.
A.NBDP B.EGC receiver C.NBDP or both D.EGC receiver or both
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.
单项选择题 There are（）NCSs in total, one in each ocean region, the AOR (E and W), IOR and POR.
