Complex sentence: Yang Jintong (born 1998) is a Chinese competitive swimmer who won the gold medal in the 800 meter freestyle at the 2015 FINA World Junior Swimming Championships in Singapore.
Split into simpler sentences: Yang Jintong (born 1998) is a Chinese competitive swimmer. He won the gold medal in the 800 meter freestyle at the 2015 FINA World Junior Swimming Championships in Singapore.