虽然该文档有正确的格式，但是由于缺乏层次信息，以至于很难处理它。
Although this document is well-formed, the lack of hierarchical information makes processing it more difficult.
第一阶段的“害虫防治”策略具有人的主观性、缺乏层次性、忽略差异性；
The former tactics is possessed with human subjectivism, lacks graduation and neglects difference.
通过引入专家系统，建立了决策调度和事件调度的分层智能调度模型，克服了离散事件系统仿真策略缺少决策分析和事件处理缺乏层次的局限性。
An expert system of decision-making is employed in the simulation system, and a layered scheduling model for event scheduling and decision-making scheduling is established.
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