Complex sentence: De Jongh has danced many leading roles at the National Ballet including those in "Romeo and Juliet", "Swan Lake", "Giselle", and "The Sleeping Beauty".
Split into simpler sentences: De Jongh has danced many leading roles at the National Ballet. She has danced many leading roles including those in "Romeo and Juliet", "Swan Lake", "Giselle", and "The Sleeping Beauty".