Complex sentence: The World Lacrosse Championships have been dominated by the United States, particularly in the men's game, where the only world championship game losses at either level was in the 1978 final and 2006 final, both to Canada.
Split into simpler sentences: The World Lacrosse Championships have been dominated by the United States, particularly in the men's game. Its only world championship game losses at either level was in the 1978 final and 2006 final, both to Canada.