Prepositions are words such as aboard, above, across, after, along, anti, around, as, at, before, beneath, below, behind, beside, by, but, beyond, between, concerning, considering, down, during, except, for, following, like, inside, into, minus, near, off, on, onto, plus, through, to, under, up, upon, with, withought and many more!! in your sentence the prepositions would be on, now, and for that i know of but there could be more!! Hope this helps!!!:)
you would finish the sentence with "an" because all if theres a vowel you say "an." if its not a vowel you say "a". but in this case its "an." hope this helpss! :))
