四级练习2012.01.22
[audio]http://sound.yywz123.com/tingbbs/cet4/cet420120122.mp3[/audio]The computer virus is an outcome of the computer overgrowth in the 1980s. (1)__________________________________________________.The origin of this term came from an American science fiction "The Adolescence of P-1" 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". (2)_________________________________.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.(3)______________________________________________.The attack is to wipe out data, to delete files, or to format the hard disk.
**** Hidden Message ***** the cause of the term of computer virus is lackness between the biological virus and evil program inficted with computers
in this way,the virus infects quickly through out the hot desk or inter the organzation when infects a .. or the ...system
...harmful virus are designed to damage system
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