oil exports by country To do this, monetary and fiscal policymakers must work together, including letting the central bank liquidate its budget deficit in extreme circumstances. But central bank independence is an obstacle, not a help, in working with the financial sector. Although an enterprise's internal trade fair eliminates or reduces some of the market transaction costs, it also brings with it the specific transaction costs of the enterprise. The main reason for this defect is also the incompleteness of information. Specifically, first, there are various contractual relationships among enterprises, including contractual relationship between enterprises and workers, contractual relationship between enterprises and managers, etc. The enterprise should supervise the work of the workers and products that it employs, as well as the managers and other personnel, and induces them to work hard for the enterprise. So, companies are signing contracts and spending on oversight and incentives. Secondly, on the one hand, corporate decision makers often need to obtain information from subordinates. On the other hand, the decision-making information of the upper level of the enterprise should be realized by passing it to the subordinate. The information transmission of these two different directions will be distorted by the increase of subordination of enterprise scale, resulting in the loss of enterprise efficiency. Once again, the subordinate of the enterprise often conceals or passes the wrong information to the superior for selfish motives, so that the superior can make decisions that benefit the subordinate. Or, the subordinate's decision to the superior only passes or executes the part that is advantageous to oneself. These will result in the loss of enterprise efficiency. Thus, the expansion of enterprises is limited. According to coase's theory, the scale of the enterprise should be expanded to this point, that is at this point to increase the cost of an internal exchange cost equals the cost through the market exchange cost and so on. Nowadays, electric vehicles are referred to as pure electric vehicles, namely, a car that USES a single battery as the energy source for energy storage. It USES the battery as the energy source to power the motor, which drives the motor and drives the car forward. In terms of appearance, electric cars are indistinguishable from everyday cars. The difference lies mainly in the power source and the driving system.