Cartoon Aircraft Series,kids playground Aircraft Castle,Outdoor Cartoon Aircraft Castle,Cartoon Aircraft Playground Equipment Zhejiang Egoal Playground Equipment Co., Ltd. , https://www.trampolineparks.plLujiao Edition 4 "Regional Urban System" ppt1, the research object is a group of cities and towns in an area, not a city; 2. The core of the urban system is the central city; 3. The urban system consists of a certain number of unique cities Composition; 4. The most essential feature of the urban system is that they are interconnected to form a whole, not just a simple spatial combination.