By John Wawrow BEIJING — Hilary Knight had a goal and assist, Alex Cavallini stopped 25 shots, and the defending Olympic champion United States defeated Finland 4-1 in the women’s hockey semifinals at the Beijing Games on Monday to set up the sixth gold-medal showdown between the Americans and Canada. The cross-border rivals will play on Thursday after Canada erupted for five first-period goals over an Olympic record span of 3:24 in a 10-3 win over Switzerland earlier in the day. The two world powers have played for the championship in every Olympic tournament but the 2006 Turin Games, when...