At least two two-way VHF radiotelephone apparatus shall be provided on every cargo ship of（）tons gross tonnage and upwards but less than 500 tons gross tonnage.

（）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.

Distress traffic is the communication（）between the station in distress and the ships, aircraft, coast radio stations, coast earth stations and rescue centers participating in the rescue work.

In case a ship is in emergency or distress in any of 4 areas, it is required to use the continuous（）alert.

Particular care should be（）in selecting CESs in areas where Ocean Regions overlap.

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

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

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

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.

The advantage of geostationary satellites is（）.