Stations in the United States of America are grouped by states arranged in the alphabetical order of their（）.

If the beacon is mounted at a wrong place, it may（）by sea water, chemicals, exhaust and vibrations.

Radio communication（）for many years and helps to save tens of thousands of lives.

Please use（）for（）.

The frequency（）the safety message will be transmitted shall be included in DSC safety call.

SafetyNet is an international service for the broadcast and automatic reception of MSI by means of direct-printing through（）system.

International Navtex service means the coordinated broadcast and automatic reception on（）khz of maritime safety information by narrow-band direct-printing telegraphy using English language.

By using（）system a ship can send a distress message and know with certainty it will be received.

Can MF/HF radiotelephone receive the MSI sent from the coast stations alone?（）

The vessel has stayed in port for seven days because she needs（）.