A yellow signal，floating in the air from a parachute，about 300 feet above the water，indicates that a submarine（）.

单项选择题A rigid replica of the International Code flag A may be shown by a vessel（）.

A.pulling a submarine cable
B.engaged in diving operations
C.engaged in underway replenishment
D.transferring explosives

单项选择题A message by flashing light consists of the call，the text，the ending，and the（）.

A.identity
B.time of origin
C.reply
D.procedure code

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”（）.

A.poor
B.bad
C.fair
D.good

单项选择题LAND-BASED AUTHORITY CONDUCTING AND CO-ORDINATING SEARCH AND RESCUE OPERATIONS IN A DESIGNATED AREA defines（）.

A.RCC
B.OSC
C.CSS
D.GPS