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. Before that, what is the nature of the enterprise itself is an issue that has been ignored by traditional microeconomic theory. In the traditional microeconomic theory, is the manufacturer's production process as a "black box", namely enterprise is abstracted into a from input to output a "black box" of the pursuit of profit maximization. The fund said last year that it would grow 1.1% in 2017 and then increase its forecast to 2%. Leakage may occur at the interface of the gasoline pipe, which leads to the use of the air conditioning system into the vehicle. If the owner found the car fumes, deal with gasoline pipeline - open interface to check engine hatch, it is easy to discern does the interface of gas leakage, for a period of time after the leakage surface will appear a layer of oil sludge. If the leakage of the gasoline pipe is found, the interface should be tightened or repaired. Point six: look at the use of borrowing. The borrower's borrowing use must be clearly understood, applicable to the business turnover, the decoration shop and so on. So investors should pay close attention to the borrowers' borrowing and repayment methods. In New York, the U.S. energy information administration (EIA) released data showing U.S. crude inventories fell by 649.5 million barrels a day in the week ended Dec. 15, beating expectations. Gasoline stocks rose by 12.37 million barrels, but the increase was less than expected.