单项选择题
A yellow signal，floating in the air from a parachute，about 300 feet above the water，indicates that a submarine（）.
A.will be coming to periscope depth B.will be coming to the surface C.is on the bottom in distress D.is in distress and will try to surface
单项选择题 A rigid replica of the International Code flag A may be shown by a vessel（）.
单项选择题 A message by flashing light consists of the call，the text，the ending，and the（）.
单项选择题 A message by flashing light consists of the call，the identity，the ending，and the（）.
