Prepositional phrases begin with a preposition and end with a noun or a pronoun. The noun or pronoun at the end of the phrase is called the object of the preposition.
Prepositional phrases act as either adjectives or adverbs.
David pointed at Kyle's bowling ball.
The painting over the television is my favorite.
When we diagram them, it's easy to see that prepositional phrases act as adjectives or adverbs because they are connected to the main diagram with a diagonal line starting from the word that they are modifying.
This is very similar to how we diagram adjectives and adverbs!
Diagram the participle on a curved, slanted line below the word that it modifies. Diagram its complements and modifiers just as you normally would.
This example shows a participial phrase with a direct object and an adverb, but participial phrases can also contain predicate nouns, predicate adjectives, adjectives, and other phrases. You'll see more examples of this in the Sentence Diagramming Reference Manual.
Infinitives are formed from verbs and act as nouns, adjectives, or adverbs. They take the form of to + verb.
Infinitive phrases consist of an infinitive and all of the infinitive's complements and modifiers. The whole phrase acts as a noun, adjective, or adverb.
I love to run marathons.
Jack waited to eat the cupcake.
This sentence diagram below shows the basic form of an infinitive phrase. Based on how the infinitive is acting (noun, adjective, or adverb), put this little tree in the right space within the sentence diagram.
In this diagram, the infinitive has a subject, a direct object, an adjective, an adverb, and a prepositional phrase. Wow!