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

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.

The priority of EGC messages is classified by（）.

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

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

Radio beacon can be activated（）in case of distress.

The advantage of geostationary satellites is（）.

What following is not among the function of SOLAS ships?（）

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

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.