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:
mainland : boat. france : ?
answer:
airplane


question:
washington : train. moon : ?
answer:
rocket


question:
airport : taxi. downtown : ?
answer:

subway