Answer:
Once can be used in the following ways:
as an adverb: I only met him once.They’ve been here once before.
as a conjunction: Once you get there, you’ll love it.
as a noun (after “for” or “at”): For once I wish you’d tell me the truth. (after “the,” “this,” or “that”): Yes, I met him, but just the once.
1
on one occasion only
