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單項選擇題

The WWNWS is a coordinated global service for the broadcast by radio of vital information on（）to marine navigation.

A.ship’s movement
B.safety
C.ship’s management
D.hazards

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單項選擇題

With the help of modern technology, ships are able to receive automated broadcast of safety messages（）.

A.by day or at night
B.almost round the clock
C.somewhat and sometime
D.from sunrise and sunset

單項選擇題

A radio determination system based on the comparison of reference signals with radio signals reflected,or retransmitted from the position to be determined,is（）.

A.DF
B.Radar System
C.DSC System
D.COSPAS-SARSAT

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