normal profit implies that At present, there are 89, 92, 95 and other labels on the market, which represent the octane value of gasoline, which means the anti-detonation of gasoline, which has nothing to do with the cleaning of gasoline. The so-called "high label gasoline is cleaner" is misleading. It is more scientific, more economical, and can give full play to the engine's efficiency according to the engine compression ratio or the requirement of the automobile instruction manual. The market is the economic contact method which is the basic content of Commodity Exchange. Under the condition of commodity economy, the premise of exchange generation and existence is social division of labor and commodity production. Because of the social division of labor, the different producers, respectively, engaged in the production of different products, did not meet the needs of themselves and others and exchange their respective product, so that the general labor products into commodities, make the product production is transformed into commodity production. It is under this condition that the market for goods to be exchanged to meet the needs of different producers is born. Therefore, the market is the product of the division of labor and the exchange of goods under the conditions of commodity economy. The market and commodity economy have inalienable internal relation. Modern economy, the interest rate as the price of money, not only restricted by many factors in the economic and social, and changes in interest rates to have a great impact on the economy as a whole, as a result, modern economists are studying the interest rate decision problem, pay special attention to the relationship between the variables and the balance of the economy as a whole, the interest rate decision theory has experienced the classical interest rate theory, Keynes's interest theory, interest rate in loanable funds theory and is-lm analysis as well as the contemporary evolution of dynamic interest rate model, the development process. According to this model, the interest rate decision depends on the supply of savings and investment needs, money supply, money demand, four factors, cause a change in the saving investment, money supply and demand factors will affect the level of interest rates. This theory is characterized by general equilibrium analysis.