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.

[EX Q]: airport : taxi. mars : ?
[EX A]: spaceship

[EX Q]: australia : airplane. canada : ?
[EX A]: car

[EX Q]: hotel : taxi. mainland : ?
[EX A]:
boat