单项选择题
The GMDSS must combine all various subsystems, because（）.
A.they all have different limitations with respect to coverage B.they all have different limitations in the technology they use C.different systems apply to different ships D.all of above
单项选择题 Which Inmarsat system applies store-and-forward messaging?（）
单项选择题 The basic concept of GMDSS is（）.
单项选择题 SOLAS vessels should be able to communicate with a shore station（）.
