Complex sentence: Curling has been featured was optional sport in the 2003 Winter Universiade in Tarvisio and become a compulsory sport since the 2007 Winter Universiade in Turin.
Split into simpler sentences: Curling has been a part of the Winter Universiade since it was featured was optional sport in the 2003 Winter Universiade in Tarvisio. It became a compulsory sport as of the 2007 Winter Universiade in Turin.