Complex sentence: Galileo's Football has gone undefeated three times in the school's history in 1988 the Lions defeated McAteer High School becoming the first football team in San Francisco History to go 12-0.
Split into simpler sentences: Galileo's football team has been undefeated three times in the school's history. In 1988, the Lions defeated McAteer High School becoming the first football team in San Francisco history to go 12-0.