从概念上讲，从第一次顾客联系到完成工作和帐单支付的整个业务表示单个宏观层次的工作单元，并具有数天到数周不等的生命周期。
Conceptually, the entire business from first customer contact, through completion of the work and payment of the bill, represents a single, macro-level unit of work, with a lifetime of days to weeks.
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