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

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.

Radiotelephony communication or radio telex communication or both will be carried out by terrestrial or satellite means,（）the equipment fitted on ship and the area in which the incident occurs.

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

Before GMDSS, if the radio officer on board is serious ill,（）.

（）by an ice-breaker, it is important to maintain a continuous listening watch on the appropriate VHF channel and to maintain a proper look-out for sound and visual signals.

（）will form the basis for distress alerting and safety calling.

SOLAS ships shall be equipped with（）.

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

All coast radio stations（）DSC installed for VHF and HF.