It should refer to the characteristics of the two cities, describing Shanghai as an egg, a vital and complete industrial chain, and Chengdu as a potato, a city that is less perfect in all aspects.

Potatoes, bloodless and fleshless, contain protein, amino acids and a variety of vitamins and minerals, especially its vitamin composition monotonous, plant foods are incomplete proteins. Eggs, on the other hand, a seemingly simple to just an oval egg, but completely different. It is a living whole, all the proteins, amino acids and so on are skillfully composed in the most perfect system.