单项选择题
It is possible for ships to receive safety message transmitted by Navtex station（）.
A.in any INMARSAT regions B.in each NAVTEX area C.at any distance D.in Areas A3 and A4
单项选择题 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.
单项选择题 The WWNWS is a coordinated global service for the broadcast by radio of vital information on（）to marine navigation.
