Verbs constitute one of the main parts of speech (word classes) in the English language.
Most combinations of tense, aspect, mood and voice are expressed periphrastically, using constructions with auxiliary verbs.
The copula verb be has a larger number of different inflected forms, and is highly irregular.
This naming convention has all but disappeared from American and British usage, but still can be found in textbooks and teaching materials used in other countries.
The verbs do, say and have additionally have irregular third person singular present tense forms (see below).
Also, many base-form verbs contain prefixes, such un- (unmask), out- (outlast), over- (overtake), and under- (undervalue).
These are the same rules that apply to the pronunciation of the regular noun plural suffix -[e]s and the possessive -'s.
The third person singular present of have is irregular: has /hæz/ (with the weak form /həz/ when used as an auxiliary, also contractable to -'s).
The form described in this section is used with third person singular subjects as the simple present tense (in the indicative mood): He writes novels all the time.
Three words ending in -ay (lay, pay and say) change y to i and add -d (laid, paid, said).
If the base form ends in a single vowel followed by a single consonant (except h, silent t, [citation needed] w, x or y), then unless the final syllable is completely unstressed the consonant is doubled before adding the -ed (ship → shipped, but fathom → fathomed).
In general this is considered something to keep the vowel before the final consonant short (i.e. if the word were spelled shiped it would have a long i.)
However, there are 2 words, control and patrol, which follow this rule even though the vowel before the final consonant is long.
For most base forms ending in c, the doubled form used is ck, used regardless of stress (panic → panicked; exceptions include zinc → zincked or zinced, arc → usually arced, spec → specced or spec'ed, sync → sometimes synched).
(The forms marked † are not used in British English, and the doubled consonant is not used for many words of non-Anglo-Saxon origin.)
Exceptions include forms such as singeing, dyeing, ageing, rueing, cacheing and whingeing, where the e may be retained to avoid confusion with otherwise identical words (e.g. singing), to clarify pronunciation (for example to show that a word has a soft g or ch), or for aesthetic reasons.
Another example of a defective verb is beware, which is used only in those forms in which be remains unchanged, namely the infinitive, subjunctive and imperative.
Some of the forms used in Early Modern English have now fallen out of use, but are still encountered in old writers and texts (e.g. Shakespeare, the King James Bible) and in archaisms.
In some verbs, a shortened form -th appears: he hath ("he has"), he doth ("he does"; pronounced as if written duth), he saith or he sayeth ("he says").
For example, several such forms (as well as other archaic forms such as yea for "yes", thy for "your", and mine enemies for "my enemies") appear in Psalm 23 from the King James Bible: For more information see Old English verbs, English subjunctive, and Indo-European copula (for the history of the verb be).
The progressive (or continuous) aspect is expressed with a form of be together with the present participle of the verb.
The perfect aspect is expressed with a form of the auxiliary have together with the past participle of the verb.
In the second person, the imperative mood is normally expressed with the base form of the verb but without a subject: Take this outside!
Inversion is also required in certain other types of sentences, mainly after negative adverbial phrases; here too do is used if there is no other auxiliary.
In referring to an action taking place regularly (and not limited to the future or to the past), the simple present is used: He brushes his teeth every morning.
Preceded by to, it forms the to-infinitive, which has a variety of uses, including as a noun phrase (To write is to learn) and as the complement of many verbs (I want to write), as well as with certain adjectives and nouns (easy to ride; his decision to leave), and in expressions of purpose (You did it to spite me).
Verbs are used in certain patterns which require the presence of specific arguments in the form of objects and other complements of particular types.
English has a number of ergative verbs: verbs which can be used either intransitively or transitively, where in the intransitive use it is the subject that is receiving the action, and in the transitive use the direct object is receiving the action while the subject is causing it.
Other common examples include open, sink, wake, melt, boil, collapse, explode, freeze, start, sell.
(This term may also include verbs used with a complement introduced by a particular preposition that gives it a special meaning, as in take to (someone).)