单项选择题
A.CSS duties are always assumed by passenger vessels，dry cargo vessels，or tankers in that order of precedence
B.The CSS must be established by mutual agreement between the ships concerned
C.A tanker should never be assigned CSS duties unless only tankers are present
D.The first vessel to arrive at the distress incident is designated as the CSS
单项选择题 Acknowledgement by you of receipt of a distress message from a vessel which，beyond any possible doubt，is not in your vicinity and is a long distance away must be made when（）.
单项选择题 If you are transmitting a distress message by radiotelephone you should（）.
单项选择题 A person who sees someone fall overboard should（）.