Data released by the American petroleum institute (API) showed that U.S. crude oil inventories fell 5.2 million barrels in the week ended Dec. 15, down from an expected 35.18 million barrels. Refinery inventories fell more than expected, while gasoline inventories rose, but were less than expected. The overall API data is good and good for oil prices. The accounting income maintains the financial capital preservation, namely, the monetary value that only requires the owner to invest is not eroded, the enterprise income exceeds the input value part is the accounting income. Accounting focuses on reporting financial results. The economic benefits insist on physical capital preservation, which can only be confirmed when the actual production capacity of the owner is saved. It is believed that only by maintaining the actual production capacity of the enterprise can the enterprise reproduce smoothly. Physical capital preservation is more meaningful than the income of financial capital preservation, but it is difficult to measure. In the 18th century, the western countries successively carried out the industrial revolution, the universal adoption of large machinery, laid the foundation for the establishment of factory system. In 1771, British man Richard arkwright1732-1792 founded the first cotton-yarn factory in the city of kron. In the 1930s and 1940s, the factory system was established in Britain, Germany and other countries. The main sex of factory system is: to carry out large-scale intensive labor; Using big machine to improve efficiency production; Implement the employment system; The division of labor is deepening and production is socialized. The establishment of factory system marks the real birth of enterprises. According to the engine displacement, divided into a miniature (1 liter), light level sedan (1-1.6 liters), intermediate (1.6-2.5 litres), senior sedan (2.5 4 liters), limousine (4 liters).