 The verbs classified as Class I in this table end in "a" or "i" in the present and subjunctive, but that vowel is lost in the past (which ends in "-ki" in this class) and in the perfect (all perfects are in "-tuk").Class II verbs, which end in "a", "i" or "u", retain this in all forms, and form their past in "-k".Class III differs from Class I only in that there is no past suffix at all, only the bare stem.