Complex sentence: The 1990 U.S. Open was the 90th U.S. Open, held June 14--18 at Course No.3 of Medinah Country Club in Medinah, Illinois, a suburb northwest of Chicago.
Split into simpler sentences: The 1990 U.S. Open was the 90th U.S. Open. The golf tournament was held June 14--18,1990, at Medinah Country Club in Medinah, Illinois, a suburb northwest of Chicago.