and e-stems. A-stems always retain the stem vowel a in the non-third-person present-tense forms, and in the third-person first past-tense forms (e.g. "kissed"). With many o-stems and e-stems, the stem vowel is dropped in these forms (e.g. o-stem "watched", e-stem "swallowed"), but there also o- and e-stem verbs which retain the vowel ( "slept", "cooked"). Rueter (2010) therefore divides verb stems into vowel-retaining stems and vowel-dropping stems.

In indicative mood, three tenses are distinguished: present/future, first past, second