Here's an example of the power of prepositions to change the meaning.
I was talking to someone about a friend who had suddenly gotten sick (the flu, it turns out). I said, "Oh, it sounds so bad, that she's IN the hospital."
He replied quickly, "It isn't that bad. She's just AT the hospital, not IN it."
That is, she hadn't been admitted, so she was not IN it. The condition wasn't so bad, so they were treating her AT the hospital.
I think most of us would get the distinction right away.
Full moon for Halloween, huh? How often does that happen? Well, almost full. I guess it'll be fully full tomorrow.