【多选题】【消耗次数：1】
机械的故障率随时间的变化大致分为（）。
①
早期故障期
②
后期故障期
③
偶发故障期
④
中期故障期
⑤
消耗故障期
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数据库的故障是指从保护安全的角度出发，数据库系统中会发生的各种故障。这些故障主要包括：（ ）、系统故障、介质故障和计算机病毒与黑客
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