HM, Liverpool What the central bank can do to prevent the threat to its independence becomes more transparent. They can announce the votes of individual board members on all matters related to the policy and publish the minutes without delay. They can hold more press conferences and be less trite in explaining their policies. They can avoid debate on issues far from their task. They can admit that politicians have a right to determine the central bank's mission objectives. At present, countries around the world is frequent use of interest rate leverage to implement macro-control, interest rate policy has become a central bank to control money supply and demand, and a major means of regulating economic, interest rate policy in the position in the central bank's monetary policy more and more important. The importance of gasoline was not recognized in the 19th century, when it was used in a great deal of kerosene. The oil refining then relied on simple distillation processes to separate the different components of the oil from the boiling point. The boiling point of the kerosene component is higher, and the use of safety when lighting lamps becomes the main product of crude oil refining, while gasoline and other components are often burned as fuel. By the mid - to late 19th century, the successful use of gasoline engines in 1886, in 1886, the gasoline engine was successfully used as a driving force, thus the importance of gasoline increased. But using distillation, only 20% of the gasoline can be extracted from crude oil. In 1911, the standard oil company have solved the problem of low gasoline yield, by William burton and Robert hamm forest thermal cracking process of the invention, the heavy quality heating gas oil cracking of light gasoline fractions, such as to overall improve the gasoline yield, thermal cracking process in 1913 won the patent license in the United States. The subsequent catalytic cracking process has further improved the gasoline yield and octane value.