A preposition shows position. A preposition is always part of a prepositional phrase.
Certain prepositions can also act as adverbs.
Here are some words that can be both preposition and adverb:
up, down, in, out, on, off, inside, outside, before, after, over, across
The word is a preposition if the word begins a prepositional phrase.
Look at these sentences. Notice the underlined preposition is at the beginning of a phrase.
I walked up the ramp.
He fell down the stairs.
Put your coat in the closet.
Toss that bug out the window.
I’ll set the table before dinner.
We can take a walk after dinner.
Please sit on this chair.
Move the newspaper off the counter.
Be careful when you go across the street.
We can use these same underlined words as adverbs. Adverbs modify verbs and tell more about the action.
Look at these sentences. Notice that now the underlined word is not part of a phrase.
Bob woke up.
The elevator went down.
Open the door and let the cat in.
I’m going out this evening.
I’ve never eaten kale before.
The dinner comes first, but I’m not sure what comes after.
The train arrived, and Sam got on.
At the second stop, he got off.
This street is too busy to get across.
Certain words are prepositions when they begin a prepositional phrase. Those same words become adverbs when they are used alone to modify a verb. Enjoy using these words as both prepositions and adverbs.