说明：  排队论，讨论单窗口单队情形，两窗口单队情形。分别计算平均等待时间，平均逗留时间，平均每分钟服务的顾客人数。
(Queuing theory to discuss the situation single-window single team, two windows one team situation. Calculate the average waiting time, average length of stay, the average number of customers per minute service.)