单项选择题
What would NOT be a distress signal?（）
A.MAYDAY sent by radiotelephone B.Continuous sounding of fog horn C.Green star shells fired from a launcher D.Square flag and ball in a vertical line
单项选择题 What would most likely prevent a SART’s signal from being detected?（）
单项选择题 What is the primary purpose for Digital Selective Calling (DSC)?（）
单项选择题 What is the primary equipment for receiving MSI? （）
