单项选择题
A.in doubt that another vessel is taking sufficient action to avoid a collision
B.altering course to starboard
C.altering course to port
D.the stand-on vessel and will maintain course and speed
单项选择题 After a vessel transmits the original distress message，what signal should be sent to allow ships to take RDF bearings?（）
单项选择题 A message giving warning of a hurricane should have which prefix when sent by radiotelephone?（）
单项选择题 A Coast Guard radiotelephone message about an aid to navigation that is off station is preceded by the word（）.