high mileage oil worth it 1) operation special car Historically, the concept of income has first appeared in economics. Adam Smith, in the wealth of nations, defined income as "the amount of consumption that is not eroded by capital", and saw it as an increase in wealth. Later, most economists inherited and developed this view. 1890, ai (Alfred Marshall Maarshell) in its "the principles of economics," the Adam Smith's "wealth increase" enterprise, introduced the concept of earnings, is proposed to distinguish the entity capital and value-added benefits of economic benefits. 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). There were two opposing views of development in the 19th century. A push performance degradation is based on the second law of thermodynamics system, it argues that, due to the dissipation of energy, the world tends to be weak, the universe tends to "heat death", the structure of the retreat, disorder tend to the maximum, the whole world over time and the process of dying; Another is based on Darwin's theory of evolution of the evolution of the concept system, it points out that social evolution is the result of the increasing division of species, the evolution and increased, structure complex and orderly, and constantly reinforced by functional evolution, all nature and human society are to develop more advanced, more orderly organization structure. The international monetary fund has strongly defended its gloomy forecast of the UK after brexit, saying a warning of a slowdown in growth is imminent.