考研网校复习专区英语阅读练习三:计算机病毒
<p> <span word="The">The</span> <span word="computer">computer</span> <span word="virus">virus</span> <span word="is">is</span> <span word="an">an</span> <span word="outcome">outcome</span> <span word="of">of</span> <span word="the">the</span> <span word="computer">computer</span> <span word="overgrowth">overgrowth</span> <span word="in">in</span> <span word="the">the</span> 1980<span word="s">s</span>. <span word="The">The</span> <span word="cause">cause</span> <span word="of">of</span> <span word="the">the</span> <span word="term">term</span> <span word="computer">computer</span> <span word="virus">virus</span> <span word="is">is</span> <span word="the">the</span> <span word="likeness">likeness</span> <span word="between">between</span> <span word="the">the</span> <span word="biological">biological</span> <span word="virus">virus</span> <span word="and">and</span> <span word="the">the</span> <span word="evil">evil</span> <span word="program">program</span> <span word="infected">infected</span> <span word="with">with</span> <span word="computers">computers</span>. <span word="The">The</span> <span word="origin">origin</span> <span word="of">of</span> <span word="this">this</span> <span word="term">term</span> <span word="came">came</span> <span word="from">from</span> <span word="an">an</span> <span word="American">American</span> <span word="science">science</span> <span word="fiction">fiction</span> <span word="The">The</span> <span word="Adolescence">Adolescence</span> <span word="of">of</span> <span word="P">P</span>-1<span word="written">written</span> <span word="by">by</span> <span word="Thomas">Thomas</span> <span word="J">J</span>. <span word="Ryan">Ryan</span>,<span word="published">published</span> <span word="in">in</span> 1977. <span word="Human">Human</span> <span word="viruses">viruses</span> <span word="invade">invade</span> <span word="a">a</span> <span word="living">living</span> <span word="cell">cell</span> <span word="and">and</span> <span word="turn">turn</span> <span word="it">it</span> <span word="into">into</span> <span word="a">a</span> <span word="factory">factory</span> <span word="for">for</span> <span word="manufacturing">manufacturing</span> <span word="viruses">viruses</span>. <span word="However">However</span>,<span word="computer">computer</span> <span word="viruses">viruses</span> <span word="are">are</span> <span word="small">small</span> <span word="programs">programs</span>. <span word="They">They</span> <span word="replicate">replicate</span> <span word="by">by</span> <span word="attaching">attaching</span> <span word="a">a</span> <span word="copy">copy</span> <span word="of">of</span> <span word="themselves">themselves</span> <span word="to">to</span> <span word="another">another</span> <span word="program">program</span>.</p><p> <span word="Once">Once</span> <span word="attached">attached</span> <span word="to">to</span> <span word="the">the</span> <span word="host">host</span> <span word="Program">Program</span>,<span word="the">the</span> <span word="viruses">viruses</span> <span word="then">then</span> <span word="look">look</span> <span word="for">for</span> <span word="other">other</span> <span word="programs">programs</span> <span word="to">to</span> <span word="infect">infect</span>.<span word="In">In</span> <span word="this">this</span> <span word="way">way</span>, <span word="the">the</span> <span word="virus">virus</span> <span word="can">can</span> <span word="spread">spread</span> <span word="quickly">quickly</span> <span word="throughout">throughout</span> <span word="a">a</span> <span word="hard">hard</span> <span word="disk">disk</span> <span word="or">or</span> <span word="an">an</span> <span word="entire">entire</span> <span word="organization">organization</span> <span word="when">when</span> <span word="it">it</span> <span word="infects">infects</span> <span word="a">a</span> <span word="LAN">LAN</span> <span word="or">or</span> <span word="a">a</span> <span word="multi">multi</span>-<span word="user">user</span> <span word="system">system</span>. <span word="At">At</span> <span word="some">some</span> <span word="point">point</span>,<span word="determined">determined</span> <span word="by">by</span> <span word="how">how</span> <span word="the">the</span> <span word="virus">virus</span> <span word="was">was</span> <span word="programmed">programmed</span> <span word="the">the</span> <span word="virus">virus</span> <span word="attacks">attacks</span>. <span word="The">The</span> <span word="timing">timing</span> <span word="of">of</span> <span word="the">the</span> <span word="attack">attack</span> <span word="can">can</span> <span word="be">be</span> <span word="linked">linked</span> <span word="to">to</span> <span word="a">a</span> <span word="number">number</span> <span word="of">of</span> <span word="situations">situations</span>,<span word="including">including</span> <span word="a">a</span> <span word="certain">certain</span> <span word="time">time</span> <span word="or">or</span> <span word="date">date</span>, <span word="the">the</span> <span word="presence">presence</span> <span word="of">of</span> <span word="a">a</span> <span word="particular">particular</span> <span word="file">file</span>,<span word="the">the</span> <span word="security">security</span> <span word="privilege">privilege</span> <span word="level">level</span> <span word="of">of</span> <span word="the">the</span> <span word="user">user</span>,<span word="and">and</span> <span word="the">the</span> <span word="number">number</span> <span word="of">of</span> <span word="times">times</span> <span word="a">a</span> <span word="file">file</span> <span word="is">is</span> <span word="used">used</span>. <span word="Likewise">Likewise</span>,<span word="the">the</span> <span word="mode">mode</span> <span word="of">of</span> <span word="attack">attack</span> <span word="varies">varies</span>. <span word="So">So</span>-<span word="called">called</span> <span word="benign">benign</span> <span word="viruses">viruses</span> <span word="might">might</span> <span word="simply">simply</span> <span word="display">display</span> <span word="a">a</span> <span word="message">message</span>,<span word="like">like</span> <span word="the">the</span> <span word="one">one</span> <span word="that">that</span> <span word="infected">infected</span> <span word="IBMs">IBMs</span> <span word="main">main</span> <span word="computer">computer</span> <span word="system">system</span> <span word="last">last</span> <span word="Christmas">Christmas</span> <span word="with">with</span> <span word="a">a</span> <span word="seasons">seasons</span> <span word="greeting">greeting</span>. <span word="Malignant">Malignant</span> <span word="viruses">viruses</span> <span word="are">are</span> <span word="designed">designed</span> <span word="to">to</span> <span word="damage">damage</span> <span word="the">the</span> <span word="system">system</span>. <span word="The">The</span> <span word="attack">attack</span> <span word="is">is</span> <span word="to">to</span> <span word="wipe">wipe</span> <span word="out">out</span> <span word="data">data</span>, <span word="to">to</span> <span word="delete">delete</span> <span word="flies">flies</span>, <span word="or">or</span> <span word="to">to</span> <span word="format">format</span> <span word="the">the</span> <span word="hard">hard</span> <span word="disk">disk</span>.</p><p> <span word="What">What</span> <span word="Kind">Kind</span> <span word="of">of</span> <span word="Viruses">Viruses</span> <span word="Are">Are</span> <span word="There">There</span>?<span word="There">There</span> <span word="are">are</span> <span word="two">two</span> <span word="main">main</span> <span word="types">types</span> <span word="of">of</span> <span word="viruses">viruses</span>：<span word="shell">shell</span>,<span word="intrusive">intrusive</span>. <span word="Shell">Shell</span> <span word="viruses">viruses</span> <span word="wrap">wrap</span> <span word="themselves">themselves</span> <span word="around">around</span> <span word="a">a</span> <span word="host">host</span> <span word="program">program</span> <span word="and">and</span> <span word="dont">dont</span> <span word="modify">modify</span> <span word="the">the</span> <span word="original">original</span> <span word="program">program</span>. <span word="Shell">Shell</span> <span word="programs">programs</span> <span word="are">are</span> <span word="easy">easy</span> <span word="to">to</span> <span word="write">write</span>,<span word="which">which</span> <span word="is">is</span> <span word="why">why</span> <span word="about">about</span> <span word="half">half</span> <span word="of">of</span> <span word="viruses">viruses</span> <span word="are">are</span> <span word="of">of</span> <span word="this">this</span> <span word="type">type</span>. <span word="Intrusive">Intrusive</span> <span word="viruses">viruses</span> <span word="invade">invade</span> <span word="an">an</span> <span word="existing">existing</span> <span word="program">program</span> <span word="and">and</span> <span word="actually">actually</span> <span word="insert">insert</span> <span word="a">a</span> <span word="portion">portion</span> <span word="of">of</span> <span word="themselves">themselves</span> <span word="into">into</span> <span word="the">the</span> <span word="host">host</span> <span word="program">program</span>. <span word="Intrusive">Intrusive</span> <span word="viruses">viruses</span> <span word="are">are</span> <span word="hard">hard</span> <span word="to">to</span> <span word="write">write</span> <span word="and">and</span> <span word="very">very</span> <span word="difficult">difficult</span> <span word="to">to</span> <span word="remove">remove</span> <span word="without">without</span> <span word="damaging">damaging</span> <span word="the">the</span> <span word="host">host</span> <span word="file">file</span>.</p>
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