My friend John has got a restaurant in a big city (城市). It is near a supermarket. He gets ten robots for the restaurant. Each robot costs (花费) 20,000 yuan. The restaurant is not big, but very popular. 现在越来越多人来这里吃晚餐。The robots have different jobs in the restaurant. Two robots cook different kinds of food; one washes the dishes; one cleans the floor and the others give food to the guests (客人). Although robots do most of the jobs in the restaurant, John is still very busy. He must do many things to keep the robots working well. 幸运的是，约翰擅长