"Commutable" is a word in ENGLISH

Little Tommy's kindergarten class was on a field trip to their local police station. There they saw pictures tacked to a big bulletin board. The label clearly read, "The 10 Most Wanted."One of the youngsters pointed to a picture and asked if it really was the photo of a wanted person."Yes," said the policeman, "the detectives want him very badly."So Little Tommy asked, while tugging on the man's belt, "Um, mister, why didn't you keep them when you took their pictures?"