Computer （1） is an intrusive （2） that infects computer （3） by inserting （4） ofitself in those files. The copies are usually executed when the file is loaded into （5），allowing them to （6） still other files, and so on. Viruses often have damaging side effectssometimes intentional, sometimes not--such as destroying a computer's hard （7） or taking up（8）space that could otherwise be used by program.Avirus is a program, made by either a （9） or not. It is not so easy to make one, butmany people know how to do it, for example, you may know that you have to know some exact computer （10） to make a computer virus.