Elevators, printers, and chillers: stock answers provided by three companies

At the 9th CIIE, Xunda Elevator is renovating elevators and escalators in old buildings, brothers are connecting printers to HarmonyOS systems, and Johnson Controls is replacing data centers and factories with more energy-efficient chillers. The homework of the incremental era is to build new ones, while the homework of the stock era is to make good use of existing ones. All three answer the latter question.