Complex sentence: He started the 2005 season by winning Dwars door Vlaanderen, and went on to win major races including the GP d'Isbergues and a stage of the Three Days of De Panne.
Split into simpler sentences: He started the 2005 season by winning Dwars door Vlaanderen. In that season, he won major races including the GP d'Isbergues and a stage of the Three Days of De Panne.