片语
radiotelegraph distress frequency无线电报遇险频率
international boundary distress frequency国际遇险呼救频率
idf international distress frequency国际遇险呼救频率
radiotelephone distress frequency watch无线电话遇险频率值班
telephone distress frequency无线电话遇险呼救频率
international distress frequency国际遇险呼救频率
DF Distress Frequency求救频率
distress radio frequency遇险无线电频率
radiotelephone distress frequency无线电话遇险频率