单项选择题
The source of energy fitted in GMDSS complying vessels must be（）.
A.the main source of energy B.emergency source of electrical power C.the reserve source of energy D.all of above
单项选择题 The NCS of INMARSAT-A system in the IOR is in（）.
单项选择题 The position of the INMARSAT satellite over the Atlantic Ocean Region-W is（）.
单项选择题 Mariners should pay much attention in the overlapped area owing to（）.
