The "fish-type duck tail" model partially overcomes the lift of the air when the car is traveling at high speed, but it does not fundamentally solve the problem of lift of the fish. After a lot of exploration and experimentation, the designer finally found a new type of model - wedge. This type of vehicle is to tilt the body forward downward, and the back of the body is as straight as a knife, which can effectively overcome lift. In a broad sense, interest rates are not limited to bank interest itself, but also to bond markets, and even to share dividends, another way of stating dividends. In fact, in the United States, the proportion of direct financing is far greater than the indirect financing, corporate bonds, debt-financed and publicly traded shares is a very important means of financing, at this time all can use the concept of interest rates for analysis. Although interest rates are expected to rise further next year, savers should not expect higher interest rates from Banks, experts have suggested. 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".