单项选择题
A message by flashing light consists of the call，the identity，the ending，and the（）.
A.reply B.text C.time D.answer
单项选择题 “How do you read?” “I read you with signal strength one”（）.
单项选择题 LAND-BASED AUTHORITY CONDUCTING AND CO-ORDINATING SEARCH AND RESCUE OPERATIONS IN A DESIGNATED AREA defines（）.
单项选择题 When my ship arrived there，their ship（）.
