An automatic car wash system is provided for processing multiple vehicles simultaneously. In this process, unreacted crotonaldehyde may be recovered from a reaction mixture obtained by the reaction of ketene with crotonaldehyde and may be recycled to the reaction system. A content selector is coupled to the network packet scanner, and selects network packets containing units of audio content from the scanned network packets based on selection criteria, including pertinence data. An object of the present invention is to provide a memory in which applied voltage is lowered and deterioration of an insulating film is prevented.