Complex sentence: He is the primary developer of the theory of Role and Reference Grammar and has done research on two American Indian languages, Lakhota (Siouan) and Yatée Zapotec (Oto-Manguean).
Split into simpler sentences: He is the primary developer of the theory of Role and Reference Grammar. He has done research on two American Indian languages, Lakhota (Siouan) and Yatée Zapotec (Oto-Manguean).