It can be either, but more likely it will have an object and be a preposition. If there is a reason to omit the noun (what it is beneath) then technically it is an adverb.
They found a cave beneath the hill. (preposition)
When they dug around the hill, they found the cave beneath. (adverb)
* It is much more common for the synonym 'underneath' to be used as a standalone adverb.
"Down" can be used both as an adverb and a preposition. As an adverb, it can describe movement towards a lower position or level. As a preposition, it can indicate the direction or location of something being lower or beneath something else.
No, it is not a preposition. Tall is an adjective and possibly an adverb.
It is never an adverb. It is always a preposition. The word "within" can be an adverb or a preposition, and the word "forthwith" (immediately) is an adverb.
It is never an adverb. It is always a preposition. The word "within" can be an adverb or a preposition, and the word "forthwith" (immediately) is an adverb.
preposition
Adverb: I had a hat on. Preposition: I didn't have any money on me.
In this adverb form of "with" meaning "accompanying," along is an adverb and with is a preposition.
Yes "throughout" is a preposition.Yes, it can be a preposition. But it can also be an adverb by itself.
No, it is not a preposition. It is an adverb.
No. It is not a preposition. Twice is an adverb.
It can be either. It can be a preposition, or it can be an adverb (walking about), or even possibly an adjective (up and about).
As an adverb, "under" describes the location of something or someone. For example: The cat is hiding under the table. As a preposition, "under" shows the relationship between two things, typically indicating that one is beneath the other. For example: The keys are under the book.