 Here is the sentence, Mary will never read the books at home. It'll help us to discuss the structure of the verb phrase within it. The verb phrase consists of the following components, an initial adverb, the verbal head read, and two phrasal categories, which we present as triangles here, the noun phrase, the books, and the prepositional phrase, at home. That both our constituents can easily be shown. The noun phrase, the books, can be pre-posed, or it can be replaced by the pronoun them, and so can the prepositional phrase at home, whose proform is there, or in an echo question, where? The central components of the verb phrase, though, are the optional specify never, and the verbal head. They build the verb phrase. But where shall we adjoin the noun phrase and the prepositional phrase? Let's redraw the tree and see how we can adjoin the two phrasal categories. Like in all other constituents, we have to insert intermediate nodes, in this case two verb bar nodes, which we write with apostrophes. And to these verb bar nodes, we can adjoin the two phrasal categories. So the verb phrase, like all other categories, has an optional specifier, a phrasal head, the verb, and, depending on the number of additional phrasal constituents, a set of intermediate V bar nodes.