Since the MAC Service is provided at an abstract interface within an end station, it is not possible to specify the total frame transitdelay precisely.
由于MAC服务在一台终端工作站内以抽象接口的方式提供，因此它不可能指定合适的总数据包传输延时。
2
Emergent events in urban rail transit threaten the safety and order of the network. Heavy events will result in operation interruption, serious train delay and also passenger delay.
突发事件威胁城市轨道交通网络的安全与秩序，严重的将导致运营中断和列车与乘客的大规模延误。
3
Unless the goods are damaged or lost in transit, there is no coverage for simply a delay or loss of market (a change in market demand for the goods) itself.