单项选择题
There are（）NCSs in total, one in each ocean region, the AOR (E and W), IOR and POR.
A.3 B.2 C.1 D.4
单项选择题 The NCC is located in the（）.
单项选择题 The GMDSS defines four sea area based on the（）.
单项选择题 The position of the POR satellite in the Inmarsat system is（）above the equator.
