Electronic commerce may be defined as the entire set of processes that support ______ activities on anetwork and involve information analysis．

单项选择题A GIS stores information about the world as a collection of thematic ______ that can be linkedtogether by geography．

单项选择题A(n) ______ is a destructive program that fills a computer system with self-replicating information，clogging the system so that its operations are slowed or stopped．