Complex sentence: Pluzhnyk was studying at Voronezh gymnasium for several years (had ejected from it because of his participating in illegal circles), after that he continue to study in Rostov-on-Don and Bobrov.
Split into simpler sentences: Pluzhnyk was studying at Voronezh gymnasium for several years until he was ejected from it because of his participating in illegal circles. After that he continued to study in Rostov-on-Don and Bobrov.