The English language has many irregular verbs, approaching 200 in normal use – and significantly more if prefixed forms are counted.
Irregular verbs typically followed more regular patterns at a previous stage in the history of English.
The regular verbs, on the other hand, with their preterites and past participles ending in -ed, follow the weak conjugation, which originally involved adding a dental consonant (-t or -d).
For example, before the Great Vowel Shift, the verb keep (then pronounced /keːp/, slightly like "cap", or "cape" without the /j/ glide) belonged to a group of verbs whose vowel was shortened in the past tense; this pattern is preserved in the modern past tense kept (similarly crept, wept, leapt, left).
Verbs such as peep, which have similar form but arose after the Vowel Shift, take the regular -ed ending.
[2] The verb forms described in this article are chiefly those that are accepted in standard English; many regional dialects have different irregular forms, such as sneak–snuck and dive-dove, common in the United States, as opposed to standard sneaked and dived respectively.
The irregular verbs of Modern English form several groups with similar conjugation pattern and historical origin.
Verbs that retain a strong-type inflection in modern English and add -[e]n in the past participle include bear, beat, beget, bite, blow, break, choose, cleave, draw, drive, eat, fall, fly, forbid, forget, forsake, freeze, get (but with past participle got in British English), give, grow, know, lie, ride, rise, see, shake, shear, slay, smite, speak, steal, stride, strive, swear, take, tear, throw, tread, wake, weave, and write.
Those that do not add -[e]n in the usual past participle include become, begin, bind, burst, cling, come, drink, fight, find, fling, grind, hang, hold, let, ring, run, seek, shed, shine, shit, shoot, shrink, sing, sink, sit, slide, sling, slink, slit, spin, spring, stand, sting, stink, strike, swim, swing, win, wind and wring.
Other verbs retain participles in -n for certain adjectival uses and distinguish them from other usage in perfect tenses ("He is drunk" vs "drunken sailor", "The shirt has shrunk" vs "shrunken hands" or "The ship was sunk" vs "sunken cheeks").
Sometimes the connection between the infinitive and the adjective (i.e. originally the past participle form) is not perceived as obvious any more, e.g. seethe – sodden.
The verb have, which is pronounced with an /æ/ sound, has a contracted third person present indicative form: has /hæz/ (weak pronunciation /həz/).
The verb say displays vowel shortening in the third person present indicative (although the spelling is regular): says /sɛz/.
For example, bore and found may be past tenses of bear and find, but may also represent independent (regular) verbs of different meaning.
Another example is lay, which may be the past tense of lie, but is also an independent verb (regular in pronunciation, but with irregular spelling: lay–laid–laid).
Their irregular inflected forms are generally single-syllable also, except for the past participles in -en like chosen and risen.
However, many additional irregular verbs are formed by adding prefixes to the basic ones: understand from stand, become from come, mistake from take, and so on.
Steven Pinker's book Words and Rules describes how mistakes made by children in learning irregular verbs throw light on the mental processes involved in language acquisition.
The fact that young children often attempt to conjugate irregular verbs according to regular patterns indicates that their processing of the language involves the application of rules to produce new forms, in addition to the simple reproduction of forms that they have already heard.