If my book bag could get polluted unless there are electirc cars, then it is not the case that my book bag wouldn't get polluted if and only if there are not electric cars or electric cars are not as safe for Bugles as one might expect provided that electricity over time tends to break down corn and corn based products in which case it's a good thing that witches ride brooms and not pencils so that in the event that electric cars break down corn there will be something with which to sweep up the corn.