Prosecutors say an 18-year-old Belleville woman was driving her vehicle 91 miles-an-hour just seconds before she hit and killed a boy riding an A-T-V eight months ago.  Samantha Trainor is facing charges of homicide by negligent driving.  Data downloaded from her car’s computer indicates she was going 75 miles-an-hour when the impact occurred in 55 zone.  Seventeen-year-old Eric J. O’Connor was killed in the town of Primrose last July.  Trainor was in Dane County court Thursday.