Form-Function Diagram: A pizza ate a cow with gray stripes.

In the sentence A pizza ate a cow with gray stripes, the noun phrase a pizza functions as the subject. The determiner (indefinite article) a function as the determinative of the noun pizza. The verb ate functions as the predicate, and the verb phrase ate a cow with gray stripes functions as the complete predicate. The noun phrase a cow with gray stripes functions as the direct object. The prepositional phrase with gray stripes functions as the noun phrase modifier of the noun cow. The noun phrase gray stripes contains the null determiner (zero article) and functions as the prepositional complement of the preposition with. The adjective phrase gray functions as the noun phrase modifier of the noun cow.

A form-function diagram is a visualization of the layers of grammar. The top identifies forms, or what words, phrases, and clauses look like. The bottom identifies functions, or what words, phrases, and clauses do. For more information about form-function diagrams, see A Form-Function Description of the Grammar of the Modern English Language: Book 1 (Level 9A) (A Form-Function English Grammar) and A Form-Function Description of the Grammar of the Modern English Language: Book 2 (Level 9B) (A Form-Function English Grammar).