THE CONJUGATION OF VERBS.
The conjugation of a verb is a regular arrangement of its moods, tenses, persons, numbers, and participles.
There are four PRINCIPAL PARTS in the conjugation of every simple and complete verb; namely, the Present, the Preterit, the Imperfect Participle, and the Perfect Participle.[256] A verb which wants any of these parts, is called defective; such are most of the auxiliaries.
An auxiliary is a short verb prefixed to one of the principal parts of an other verb, to express some particular mode and time of the being, action, or passion. The auxiliaries are do, be, have, shall, will, may, can, and must, with their variations.