A.complicated circumstances
B.changeable atmospheric pressure
C.large density of traffic
D.some strong signals from unwanted satellites
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A.besides the polar regions
B.including the North Pole and the South Pole
C.above 70N and below 70S
D.as far north and south 70
A.Space segment, NCC, RCC, SES and CES
B.Space Segment, a satellite system, C system, NCC and NCS
C.Space Segment, NCC, NCS,CES and SES
D.A system, C system, satellite system, earth stations and NCS
A.4
B.9
C.8
D.5
A.the weather over there is always terrible
B.the condition there is complicated
C.the signals are too strong
D.their SES may receive the signals from unwanted satellite
A.sometimes
B.all times
C.never
D.partly
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Every lifeboat which is fitted with a fixed two-way（）radiotelephone apparatus with an antenna which is separately mounted shall be provided with arrangements for sitting and securing the antenna effectively in its operating position.
For COSPAS-SARSAT system,（）usually transmit initial COSPAS-SARSAT alert.
（）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.
Radio communication（）for many years and helps to save tens of thousands of lives.
In case a ship is in emergency or distress in any of 4 areas, it is required to use the continuous（）alert.
Monitoring is especially important in a highly automated system which is dependent on careful（）procedure and format.
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.
Ship-to-ship distress alerting should be conducted by（）.
As each MSI message will have a unique identity, the printing of messages already received correctly is（）.
COSPAS-SARSAT is intended to be used for（）.