A prepositional phrase is a phrase that begins with a preposition and ends with a noun or a pronoun (which is the object of the preposition). Now If you have a complex sentence, the dependent clause will start with a subordinating conjunction witch is sort of similar with a preposition because it is a prepositional phrase, but what always begins a dependent clause is a subordinating conjunction (so it won't confuse you). Here are some examples of prepositional phrases: the cat is (under the table). PPP before you go!! Parentheses around Prepositional Phrases! That's what my teacher taught me!