I think its accepted now based on another reply. But i just wanted to add that, to me, "I need a library book." and "I need a book from the library." could mean two different things. "I need a library book" sounds like they need any book from any library where as "I need a book from the library." sounds like they need a specific book from a specific library. I see how your answer could be correct, but i dont think it should be accepted as the main answer. Bc your point is that in english, library book and book from the library mean the same thing and I've pointed out how (to me) one sentence implies a bit more than the other. Which makes it less of a fact that they mean the same and more of a subjective opinion. But this isnt English this is spanish and there comes a time when you have to stop filtering the spanish youre learning through your learned English sentence structure. Being resistant to that could inhibit your ability to learn it properly. Learning a language isnt just vocabulary and word for word translations. Its also about learning to form sentences the way the language is intended to and you cant do that if youre too concerned with if the English translation sounds exactly like how a native English speaker would say it.