Input (grade 9): Baby wore the mask in three episodes (The Mask Is Always Greener on the Other Side (Part 1), Baby's Wild Ride and Mutiny of the Bounty Hunters).
Output (grade 9): Wore the mask on three occasions: part one of "The Mask is Always Greener on the Other Side", "Baby's Wild Ride", and "Mutiny of the Bounty Hunter".