图2：与图1中显示的相同的零售系统用例图。
Figure 2: Use Case diagram for the same retail system shown in Figure 1.
电力零售市场对现有的电网自动化系统提出了改进要求。
Power grid automation system needs to be updated in the new environment.
在该系统中，两制造商作为委托人，零售商作为代理人。
The system has two manufacturers as principals and one retailer as agent.
该系统还会提供一些零售商的优惠券和其它信息，另外它还能帮你找到停车位。
The system will offer coupons and information about retailers, plus help find parking.
该系统还会提供一些零售商的优惠券和其它信息，另外它还能帮你找到停车位。
The system will offer coupons and information about retailers, plus help find parking.
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