Complex sentence: Maria Callas, Commendatore OMRI (December 2,1923--September 16,1977), was an American soprano of Greek origin, and one of the most renowned and influential opera singers of the 20th century.
Split into simpler sentences: Maria Callas, Commendatore OMRI (December 2,1923--September 16,1977), was an American soprano of Greek origin. She was one of the most renowned and influential opera singers of the 20th century.