Verbs constitute one of the main word classes in the English language. Like other types of words in the language, English verbs are not heavily inflected. Most combinations of tense, aspect, mood and voice are expressed periphrastically, using constructions with auxiliary verbs.
Generally, the only inflected forms of an English verb are a third person singular present tense form in -s, a past tense, a past participle (which may be the same as the past tense), and a form ending in -ing that serves as a present participle and gerund. Most verbs inflect in a simple regular fashion, although there are about 200 irregular verbs; the irregularity in nearly all cases concerns the past tense and past participle forms. The copula verb be has a larger number of different inflected forms, and is highly irregular.
A typical English verb may have five different inflected forms:
- The base form or plain form (go, write, climb), which has several uses—as an infinitive, imperative, present subjunctive, and present indicative except in the third-person singular
- The -s form (goes, writes, climbs), used as the present indicative in the third-person singular
- the past tense or preterite (went, wrote, climbed)
- The past participle (gone, written, climbed) – this is identical to the past tense in the case of regular verbs and some irregular ones (here the first two verbs are irregular and the third regular)
- The -ing form (going, writing, climbing), used as a present participle, gerund, and (de)verbal nounThe verb be has a larger number of different forms (am, is, are, was, were, etc.), while the modal verbs have a more limited number of forms.
Some forms of be and of certain other auxiliary verbs also have contracted forms ( 's, 're, 've, etc.).
In English, verbs frequently appear in combinations containing one or more auxiliary verbs and a nonfinite form (infinitive or participle) of a main (lexical) verb.
The first verb in such a combination is the finite verb, the remainder are nonfinite (although constructions in which even the leading verb is nonfinite are also possible – see below). Such combinations are sometimes called compound verbs; more technically they may be called verb catenae, since they are not generally strict grammatical constituents of the clause.
- The dog was barking very loudly.
- My hat has been cleaned.
- Jane does not really like us.
As the last example shows, the words making up these combinations do not always remain consecutive.
Tenses, Aspects and Moods
The means English uses for expressing the three categories of tense (time reference), aspect and mood are somewhat conflated. English has only limited means for expressing these categories through verb conjugation, and tends mostly to express them periphrastically, using the verb combinations mentioned in the previous section. The tenses, aspects and moods that may be identified in English are described below (although the terminology used differs significantly between authors). Note that in common usage, particular tense–aspect–mood combinations such as "present progressive" and "conditional perfect" are often referred to simply as "tenses".