在典型的servlet模型中，一个打开的连接意味着一个不执行任何操作的专用线程，它将一直等待，直到在响应事件时更新客户端。
In the classic servlet model, an open connection means a dedicated thread is doing nothing but waiting until it needs to update the client in response to an event.
地下洞室群的交通运输系统是一种典型的离散事件动态系统，难以用解析方法计算的数学模型来描述。
The traffic transportation system of underground structure group is a kind of typical discrete event dynamic system, which is difficult to describe with analytic mathematic models.
HTA模型被用来围绕医师抽取一个病人血样的事件组合故事，来支撑典型场景的基于目标的结构。
The HTA model was used to compose the story around the event of a phlebotomist drawing a patient's blood that supports the goal-based structure of the scenario.
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