How can there be Liangping District and the Seventh Bridge?

Liangping area appears because of the control of geological structure, stratigraphic distribution and lithology, and the seventh bridge appears because of the connection point.

1, Liangping landform is controlled by geological structure, stratigraphic distribution and lithology, and influenced by hydrological action. It presents a natural landscape with three mountains and five ridges, two troughs and one dam, rolling hills and six streams flowing out, forming a special landform with mountains, hills and dams alternating, mainly in mountainous areas. There are Dongshan, Xishan and Zhongshan in the territory, all in the northeast direction, arranged in parallel and not connected with each other. The mountain area is 500- 122 1 m above sea level, covering an area of 606.5 square kilometers, accounting for 32% of the total area of the whole region. Dongshan (Huangnitang anticline) and Xishan (Xia Mingyue anticline) are formed into long and narrow troughs (Dongshan South Trough and Xishan Libai Trough) due to the limestone of Jialingjiang Formation exposed at the top of the mountain being dissolved by water, and the sandstone of Xujiahe Formation on the two wings is opposite to Xialing Mountain, so it is one mountain, two ridges and one trough. The limestone of Jialing River at the top of Zhongshan (Nanmenchang anticline) has not been exposed and dissolved, and it still maintains the type of one mountain and one ridge. There are many undulating hills between the three mountains, with deep hills in the southeast and northeast and shallow hills in the middle and northwest. Area 1 184.9 square kilometers, accounting for 62.9% of the total area of the region.

2, a painting can be finished in one stroke, then the beginning of painting must have a starting point and an end point. The point on the other map is the intersection-we must pass it. It is a point that can go up and down, and there is a point that can go in and out. If there is an edge in, there must be an edge out. It can't be a point that can enter and exit, it becomes the end point, and it can't be a point that can't enter, it becomes the starting point. Therefore, the total number of edges entering and leaving the intersection should be even, that is, the intersection is even. If the starting point and the ending point are the same point, then it also belongs to the type of going in and going out, so it must be an even point, so all the points on the graph are even points.