Ten major difficulties facing city's sustained development are summarized, including too much land occupied, traffic jam, difficulty in parking, difficulty in walking, high energy consumption, low efficiency, poor public security, unlivableness, frequent traffic accidents and high investment in traffic facilities. The basic formulas for solving these difficulties are presented. For example, traffic supply density > traffic demand density is the basic formula for addressing traffic congestion. Only when the inequality becomes realistic can the traffic problem be soloved. Based on every basic formulas, a new unimpeded city mode is sublimated from many complex city mode schemes. Once the new mode in introduced, the ten major difficulties will be solved in an all-round way, and the city's livableness index will be doubled. For the sustainable developing city pattern, the centre position should not be locked at a certain place like in the case of playing chess, instead, the positions of every centre should be formed and vary along with the development just like in the case of playing a game of go. That is the doctrine of nonspecific city centre.