'The popcorn comes at a cost', 'The popcorn isn't really free', 'The popcorn Price $10', 'You have to pay for the popcorn' or, simply, 'The popcorn is not free'. The assertion, 'You can take your baby about the flight free of demand' would be in opposition to 'You need to fork out to just take your newborn on a plane' or 'It's not free', or informa