A、They invade the computer and make it a place for manufacturing. B、They spread throughout the whole system by quickly copying t

The computer virus is an outcome of the computer overgrowth in the 1980s. The cause of the term "computer virus" is the likeness between the biological virus and the evil program infected with computers. The origin of this term came from an American science fiction "The Adolescence of P-l" written by Thomas J. Ryan, published in 1977. Human viruses invade a living cell and turn it into a factory for manufacturing viruses. However, computer viruses are small programs. They expand by attaching a copy of themselves to another program. Once attached to the host program, the viruses then look for other programs to "infect". In this way, the virus can spread quickly throughout a hard disk or an entire organization when it infects a LAN or a multiuser system. The timing of the attack can be linked to a number of situations, including a certain time or date, the presence of a particular file, the security level of the user, and the number of times a file is used. Likewise, the mode of attack varies. So called "benign" or the harmless viruses might simply display a message, like the one that infected IBM’s main computer system last Christmas with a season’s greeting. Malignant or the harmful viruses are designed to damage the system. The attack is to wipe out data, to delete files, or to format the hard disk.
Questions 22 to 25 are based on the passage you have just heard.
22. How did the name of "computer virus" come into being?
23. What is the way that the computer viruses infect the computer system?
24. What is a "benign" virus?
25. What can a "malignant" virus do to your computer?