English verbs: form and function
Recall from Chapter 14 that lexical verbs like adore are open-class elements, while auxiliary verbs belong to a closed class. We also saw in Chapter 14 that the English auxiliaries can be divided into two subcategories: modal auxiliaries and primary auxiliaries. Modal auxiliaries like can and must are responsible for introducing epistemic mood (relating to knowledge) or deontic mood (relating to obligation or permission) into the clause. The primary auxiliaries have and be introduce grammatical aspect and passive voice: while have introduces perfect aspect, beintroduces either progressive aspect or passive voice. Each type of auxiliary requires the verb that follows it to occur in a certain form: the modal requires a bare infinitive (e.g. must write);the perfect auxiliary requires a ‘past’ or perfect participle (e.g. have written) and the passive auxiliary requires the same form (e.g.be written).The progressive auxiliary requires a ‘present’ or progressive participle (e.g.be writing).As we mentioned in Chapter 11,the traditional labels ‘past’ and ‘present’ participle are rather misleading because participles are not finite verb forms, which means they can occur in past, present or future contexts.
As these examples indicate, each English verb has a number of different grammatical forms. For example, the verb write has five morphologically dis tinct forms, which represents the typical case for English verbs: (to) write, writes, wrote, writing, written. The verb go also has five forms:(to) go, goes, went, going, gone. In contrast, the verb put only has three morphologically distinct forms: (to) put, puts, putting. The list for be is the longest with eight distinct forms:(to) be, am, are, is, was, were, being, been. Table 18.1 summarises the properties of these forms. Each distinct form is marked once in bold type. As this table shows, a single verb form in English is typically compatible with subjects that reflect a wide range of different person and number features, exceptions being the third person singular present tense form, and the richer set of forms representing the verb be. This explains why English does not usually license implicit subjects in main clauses (because the person and number features of the subject are not usually marked on the verb). Recall that only past and present tense forms are finite (marked for tense), while infinitives and participles are non-finite.
