instruction:
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.
question:
hospital : ambulance. airport : ?
answer:
train


question:
mars : spaceship. office : ?
answer:
car


question:
downtown : subway. mars : ?
answer:

spaceship