The preposition that is used in the given sentence above is the word "at", so the prepositional phrase is "at least once". Therefore, the words that are part of the prepositional phrase in this sentence are the words least and once. Hope this answers your question. Have a great day!
The letter was post by his father
<span>there are a great many different key characteristics of poetry.
These characteristics include a rhyming and prose scheme in the
poetry. </span>
