Complex sentence: The Secretariat Stakes is a Grade 1 flat horse race in the United States for three-year-old thoroughbreds run over a distance of 1¼ miles (approximately 2,000 metres).
Split into simpler sentences: The Secretariat Stakes is a Grade 1 flat horse race in the United States for three-year-old thoroughbreds. It is run over a distance of 1¼ miles (approximately 2,000 metres).