Final answer:
The word 'expensive' best fills the blank in the sentence 'Collecting cars is a(n) _____ hobby. It costs a lot of money.' This is because expensive is a term that describes things that cost a significant amount of money.
Step-by-step explanation:
Collecting cars is an expensive hobby. It costs a lot of money. In English language usage, the word 'expensive' accurately describes goods, services, and hobbies that require a significant amount of money. An example could be owning and maintaining a luxury car. Therefore, 'expensive' provides a fitting description of the hobby of car collecting, given the substantial financial investment typically involved.
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