Complex sentence: The 1978 U.S. Open was the 78th U.S. Open, held June 15--18 at Cherry Hills Country Club in Englewood, Colorado, a suburb south of Denver.
Split into simpler sentences: The 1978 U.S. Open was the 78th U.S. Open. The golf tournament was held June 15--18,1978, at Cherry Hills Country Club in Englewood, Colorado, a suburb south of Denver.