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. In 1934, professor rei, of the center for fluid mechanics, used model cars to measure the aerodynamic drag of various bodies in wind tunnels In his theory, money supply is controlled by the central bank and is an exogenous variable with no interest rate elasticity. At this point, monetary demand depends on people's psychological "liquidity preference". Philip Hammond has been trying to persuade conservatives that tax increases and spending cuts are needed to reduce the deficit. 2. Accounting earnings are based on the assumption of accounting instalments, which refers to the production and operation results of a certain period of time. Early accounting earnings is calculated according to the cash basis, and the modern accounting earnings is according to the classification current income and expenses of accrual basis, after the appropriate ratio calculated. However, the benefits of cash determination are more acceptable to users.