Fluctuating bars of service, random outages, not running entirely, shutting down the phone - the complaints on the Apple forums and throughout the blogosphere have ranged pretty extensively.

起伏不定的信号格，随意就无服务，完全不工作，电话停机——从苹果社区到博客世界，已经是牢骚遍地。

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So, maintenance service systems have two own peculiarities: a wide range of fluctuating of demands of spare part and high cost of outing of stock.

因此维修服务系统又有自身的两个特点：备件需求波动量大和缺货成本很高。

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