CHICAGO Barry Zito threw seven strong innings and the San Francisco Giants beat the Chicago Cubs 6-3 onTuesday night for a sweep of a day-night doubleheader. Zito (1-1) pitched for the first time since leaving his start onApril 16 with a right foot sprain. He allowed four hits and tworuns, leading the Giants to their seventh straightwin. Brian Wilson got his 24th save.