We call this database the " virus definition file " . when an antiviral program scans a file for viruses , it compares all the signatures of all viruses in the database with the signatures in that file 我们称这个数据库为"病毒定义文件" .当杀毒程序扫描文件病毒时,它用数据库里面的所有病毒的签名跟文件里面的签名对比