In (3a), the verb root -baalbecomes baadwhen it is followed by causative -is-, applicative -ilor perfective -idi. As seen in (3b) the prefective in realized [idi] when the preceding vowel is /i/, /u/ or /a/. In (3c), however, when the preceding vowel is /e/ or /o/, there is a vowel height harmony and the perfective suffix is realized -ele. In response to this perfect complementarity, a single u...