TASK DEFINITION: Two analogies that relate places/locations to the associated travel mode is given in the form "A : B. C : ?". "A : B" relates place A to travel mode B. Your task is to replace the question mark (?) with the appropriate travel mode for the given place C, following the "A : B" relation.
PROBLEM: airport : train. mainland : ?

SOLUTION: boat

PROBLEM: mars : spaceship. island : ?

SOLUTION: boat

PROBLEM: mars : spaceship. hospital : ?

SOLUTION:
ambulance