short run economic profit Gasoline is produced and sold according to the brand name, and the specifications of the brand are regulated by national gasoline product standards and are related to different standards. At present, there are 3 gasoline license plates in China (IV), which are 90, 93 and 97 respectively. The state (V) is 89, 92 and 95 respectively (98 in the appendix). The number of gasoline is divided by octane number. For example, gasoline on 97 refers to a gasoline fuel equivalent to 97 percent of isooctane and 3 percent of n-heptane resistance. The larger the label, the better the anti-knock performance. Depending on the engine compression ratio, you should choose the different brand of gasoline, which will be indicated on the manual of each vehicle. A mid-range sedan with a compression ratio of 8.5-9.5 should generally use the 90 (country IV) gasoline, and the car with a compression ratio of 9.5 should use the gasoline of 93 (country IV). It is our responsibility to achieve our goals in the right way in 2018, and we have this opportunity. In terms of the purchase of intermediate products in the market, because a lot of manufacturers are generally buy goods from a handful of suppliers, it is beneficial to this a few suppliers to achieve economies of scale and reduce the cost of production. Moreover, market competition pressure between intermediate product suppliers forces suppliers to reduce production costs. In addition, when a few suppliers in the face of many intermediate products of demanders, these a few suppliers can be avoided due to the limited market demand caused by unstable, the loss that may lead to maintain a stable overall sales.