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單項選擇題

The quality of the message can be affected by（）.

A.climate
B.sunshine
C.human beings
D.both a and b

單項選擇題

The complying vessels can transmit ship-to-shore distress alerts by at least（）.

A.One means, whether satellite or terrestrial techniques
B.Two means, whether satellite or terrestrial techniques
C.Two separate and independent means, each using different radio communication services
D.Two means, such as MF DSC and HF DSC