To read more Hybrid cars, which add an internal combustion engine to pure electric vehicles, aim to reduce the pollution of cars and improve the mileage of pure electric vehicles. Hybrid vehicles have serial and parallel structure. The difference between the income and the total income has been realized The concept of accounting income is called accounting income. According to the traditional view, the accounting income refers to the difference between the realized income and the corresponding expenses. It has the following characteristics: Economic profits in perfect competition and monopolistic competition market has a special purpose, a positive profit can attract more enterprises to enter the market, increasing competition and push the market equilibrium price low, exclude some enterprises lack of competitiveness in the market, to achieve long-term equilibrium; On the contrary, negative economic profit can eliminate some of the original enterprises in the market, because the supply is reduced, the market equilibrium price will be pushed up, and the long-term equilibrium will be achieved. The result of the two cases is that economic profits disappear from each manufacturer and the manufacturer's total income is at the lowest point of average cost. Famous British economist hicks and others argue that the above theory did not consider the factor of income, and therefore unable to determine the level of interest rates, in 1937, and puts forward the is-lm model on the basis of general equilibrium theory. It establishes a theory of interest rates and income at the same time that the four factors of savings and investment, money supply and monetary demand interact.