The frequency 518KHZ will be used to transmit（）and（）wanings in NAVTEX.

单项选择题Distress alerts will be relayed on the（）when the RCC considers it necessary.

A.dedicated system
B.MSI broadcasts
C.518KHZ
D.channel 16

单项选择题The WWNWS is a coordinated global service for the broadcast by radio of vital information on（）to marine navigation.

A.ship’s movement
B.safety
C.ship’s management
D.hazards

单项选择题With the help of modern technology, ships are able to receive automated broadcast of safety messages（）.

A.by day or at night
B.almost round the clock
C.somewhat and sometime
D.from sunrise and sunset

单项选择题A radio determination system based on the comparison of reference signals with radio signals reflected,or retransmitted from the position to be determined,is（）.

A.DF
B.Radar System
C.DSC System
D.COSPAS-SARSAT

单项选择题What information will a distress alert contain?（）

A.nature of distress
B.type of assistance required
C.course and speed and time at which the information was recorded
D.A, B, C are all right