单项选择题
A Navtex station in each NAVAREA is usually allowed to have（）for transmission.
A.10 minutes every 4 hours B.half an hour every other hour C.irregular period of time D.5 minutes every two hours
单项选择题 The NAVTEX receiver can be mounted on（）.
单项选择题 The concept of NAVTEX is of a（）system for the broadcast and receipt of MSI.
单项选择题 The broadcast of MSI is made on two dedicated systems. “dedicated” means（）.
