一所德国大学校园中的咖啡价格若干年前我访问一所德国大学时,在学校的楼内想买一杯咖啡,我有两个选择:在楼内的自助餐厅购买或在自动售货机上购买,当时,自助餐厅仍在营业,所以我在该餐厅里买了一杯咖啡。傍晚7点,我回来还想再买一杯咖啡,但自助餐厅已经关门了,我只能去自动售货机上购买了,但我发现一杯咖啡此时的售价要比白天的售价 When I visited a German university a few years ago, I wanted to buy a cup of coffee in the school building. I had two choices: buying at a cafeteria in the building or at a vending machine At that time, the cafeteria was still open, so I bought a cup of coffee in the restaurant. At 7 p.m., I came back and wanted to buy another cup of coffee, but the cafeteria had closed and I could only go to the vending machine for a purchase, but I found that the price of a cup of coffee was higher than it was during the day