Comment: In Lezg. the root -a is also used with preverbs (aw-a,al-a,gal-a,gʷ-a etc.). The two stems (*ʔa and *ʔi; *i sometimes changes to u due to the labialising influence of some class prefixes) are opposed in most languages, but it is difficult to separate them from each other. In some cases they are opposed in tense/aspect (e.g. in Archi), but in most cases *ʔa tends to mean 'to be (available), to have', while *ʔi is a simple verb of existence. The original difference must have been aspectual, and the two stems were probably connected by a usual Ablaut *a / *i.