supported by over 30 cities! When "replacing an old house with a new one", the "three accounts" must be settled first. How is the "trade-in" of a house different from the mobile phones and home appliances we are familiar with? How can we make the chain of "old houses for new ones" truly circulate, thereby driving the linkage between the primary and second-hand housing markets? Here, we need to settle the “three accounts” first.