1. Imperfects in -e, -a appear usually in pure stems with athematic inflection or adding an -u in every form, which is normally an Past ending at least for some persons. Other endings can also be added to this stems.
NOTE. -u is rare in the Present and frequent in the Imperfect, and the contrary has to be said of -i.
Opposed to the Present, the stem in -e or -a is often a Past stem.
2. The basics of the Imperfect vowel stems are thus the opposition to Presents:
a. Present -i (thematic or semithematic), Imperfect -e; as, mnio / mne, be mad.
b. Present -i, Imperfect -a; as, alkio / alka, be hungry.
c. Present -e/-o, Imperfect -e; as, lege / lege, collect, speak.
d. Present -e/-o, Imperfect -a; as, gnte / gntau,know.
3. The use of the forms in -u is usually related to the Past (and sometimes the Perfect), as a suffix or ending. It can be -u, -au, -eu, -eue, -aua, -eua, -aue.
4. The -i/-i is scarcely used for Past stems; as, audhio / audhiui, hear. The stem is sometimes lengthened in -e/-i, often to help avoid the loss of consonants in the Imperfect in -s.