profitability of a firm Then the interest rate theory of the loan is the interest rate theory of neoclassical school, which is proposed to correct Keynes's theory of "liquidity preference". In some ways, the theory of interest rate can be regarded as a synthesis of classical interest rate theory and Keynesian theory. (2) actual income -- the increase of material wealth; Quality control indicators include: gasoline antiknock property (research octane number, motor octane number, antiknock index), sulfur content, vapor pressure, contents of olefins, aromatics, benzene content, corrosion, distillation range, etc. In January 2014, the national general motors (gm) IV standard was used. The state administration of quality supervision and inspection and the national standards commission issued the mandatory national standards for motor vehicles in phase V. The plan is to be implemented at the end of 2016. The sulfur content is the most critical environmental protection indicator in vehicle gasoline. In order to further reduce the emission of vehicle pollutants, the national V standard lowers the sulfur content limit from 50ppm in the fourth stage to 10ppm, which is 80% lower. Manganese has the potential risk to human health, and the vehicle emission control system will also have adverse effects. According to the principle of prevention, the limit value of the manganese content indicator is reduced from 8mg/L in the fourth stage to 2mg/L, which stipulates that no artificial addition is allowed. In order to further reduce the photochemical pollution caused by the evaporation of gasoline, and reduce the gas intake system of the automobile engine, the national five standard reduced the level of olefin from 28% to 24% in the fourth stage. Due to the decrease of octane number caused by the reduction of sulfur and manganese, the number of gasoline used in phase V was adjusted from 90, 93 and 97 to 89, 92 and 95 respectively. At the same time, considering the development trend of the automobile industry, the index requirements of motor gasoline are added in the standard appendices. 2. Predictability. The plan is made before the action, which aims to achieve the goals of the future, and to accomplish the next tasks and tasks. It looks like a big box and has doors and Windows, which people call "box cars". It is named "sedan" in the catalog because it looks like the "sedan chair" of the European ladies used for travel and other occasions. The marxist theory holds that the profit under the capitalist system is the transformation form or phenomenon of surplus value, which manifests as the balance of commodity value over cost price. That is, the total amount of the proceeds of the sale of the goods by the capitalist exceeds the balance of his prepaid capital. Profit from a home variable capital purchase Labour created in the process of production of surplus value, also is the surplus labor hiring workers create surplus value, can change capital proliferation. But it is manifested in the phenomenon as the capital increase of capital of capital of capital. Under the conditions of open economy, the scale of international capital flows is huge, which greatly exceeds international trade volume, indicating the great development of financial globalization. The impact of interest-rate differentials on exchange rate movements is more important than in the past. When a country tightening credit, interest rates will rise, character formed in the international market interest rate difference, will cause the short-term funds internationally mobile, capital generally always is flowing from countries with low interest rates to countries with high interest rates. Full market competition will make economic activity full of vigor and vitality.