Completers and Modifiers: Words That Act as Completers
The role of completer may be played by a noun, a pronoun, or a word that describes the subject.
The rowdy girls were making trouble. (Noun completer)
A noun names a thing, person, place, or idea. A pronoun takes the place of a noun and makes it possible to avoid repeating that noun. Chapter 13 discusses pronouns in more detail. The kind of completer that describes the subject is a modifier as well as a completer. The later part of this chapter will explore modifiers in more detail.
The cop finally arrested them. (Pronoun completer)
Behavior like that is crazy. (Completer describes the subject)
Click here for a list of verbs that take gerund and infinitive completers.