Diagramming PhrasesHere is everything you need to know about diagramming phrases. It makes an excellent reference book for your classroom or personal use. Learn more here. 
It's easy to see that these act as adjectives and adverbs because they begin with a diagonal line coming from the word that they are describing.  To give you a better idea of how they are used, I've also included a diagram of the following sentence: Running marathons in the summer is hot.  In the above sentence, the word marathons is a direct object. If you have a predicate noun or a predicate adjective after a gerund, diagram it like this:  Participial phrases always act as adjectives. They go on a curved, slanted line below the word that they modify. If the participle has a direct object, diagram it like this:  If the participle has a predicate noun or a predicate adjective, diagram it like this:  Infinitive phrases are versatile! They can act as nouns, adjectives, or adverbs. This little diagram 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 and a direct object:  If the infinitive has a predicate noun or a predicate adjective, diagram it like this:  These act as nouns. The appositive itself goes in parenthesis next to the noun that it is restating, and any modifiers within the phrase should be diagrammed under the noun that they are restating.  These are diagrammed just like other verbs.  |
