Complex sentence: Hilary Stellingwerff (born August 7,1981, London, Ontario) is a Canadian track and field middle-distance athlete who competed in the 1500m event at the 2012 Summer Olympics.
Split into simpler sentences: Hilary Stellingwerff (born August 7,1981, London, Ontario) is a Canadian track and field middle-distance athlete. She will compete in the 1500m event at the 2012 Summer Olympics.