Complex sentence: When she reached 15 in 2003, Xu progressed to the Europe class (then an Olympic class) according to International Sailing Federation (ISAF) rules, and switched to coach Liu Xiaoma, the husband of her old coach Zhang Jing.
Split into simpler sentences: When she reached 15 in 2003, Xu progressed to the Europe class (then an Olympic class) according to International Sailing Federation (ISAF) rules. She switched to coach Liu Xiaoma, the husband of her old coach Zhang Jing.