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:
island : boat. mainland : ?
answer:
boat


question:
hawaii : airplane. mainland : ?
answer:
boat


question:
island : boat. spain : ?
answer:

airplane