ABSTRACT
Verbs are an open word class (see B1). In terms of grammar (rather than lexis) they are the most important word class because they are the central element in clauses (see A7); each full clause must have a verb, and they determine what other elements will be present. In this book, auxiliary verbs are treated as a separate word class ('auxiliaries') as they are a closed class (see A6). It is main (or lexical) verbs that are the topic of this section.
