软件开发的螺旋模型综合了瀑布模型和演化模型的优点，还增加了(58)。采用螺旋模型时，软件开发沿着螺线自内向外旋转，每转一圈都要对(59)进行识别和分析，并采取相应的对策。螺旋线第一圈的开始点可能是一个(60)。从第二圈开始，一个新产品开发项目开始了，新产品的演化沿着螺旋线进行若干次迭代，一直运转到软件生命期结束。

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Most　computer　systems　are(71)to　two　different　groups　of　attacks:　Insider　attacks　and　outsider　attacks.　A　system　that　is　known　to　be(72)to　an　outsider　attack　by　preventing(73)from　outside　can　still　be　vulnerable　to　the　insider　attacks　accomplished　by　abusive　usage　of(74)users.　Detecting　such　abusive　usage　as　well　as　attacks　by　outsides　not　only　provides　information　on　damage　assessment,　but　also　helps　to　prevent　future　attacks.　These　attacks　are　usually(75)by　tools　referred　to　as　Intrusion　Detection　Systems.

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Because　Web　servers　are　platform.　and　application(66),　they　can　send　or　request　data　from　legacy　or　external　applications　including　databases.　All　replies,　once　converted　into(67)mark　-　up　language,　can　then　be　transmitted　to　a(68).　Used　in　this　way,　Intranets　can(69)lower　desktop　support　costs,　easy　links　with　legacy　applications　and　databases　and,(70)all,　ease　of　use.