long run profit maximization perfect competition The independent of interest is of positive significance to show the active role of the fund users in the reproduction process. Security is very important, reduce risk is big potential! (3) monetary benefits -- increase the monetary value of assets. There are both measurable and unquantifiable benefits in these three different forms of income. Among them: mental income is too strong to measure, monetary gain is easy to measure because of the static concept of value change. Economists, therefore, focus only on actual earnings. There is no risk of this arbitrage. Range and once the two currencies yield, the yield of arbitrage mechanism will make two currencies are equal, that is, different interest rates in the currency of the country there is inherently a trend towards an equalization and trend, it is the interest rate index key aspects of the impact of foreign exchange to, also is our interpretation and grasp the key interest rate index. Interest rate, in the form of expression, refers to the ratio of the amount of interest to the total amount of borrowed capital in a certain period of time.  the interest rate is the interest level per unit time of the unit currency, indicating the interest rate. Economists have been looking for a theory that can fully explain the structure and change of interest rates. Interest rates are usually controlled by the central bank of the country and administered by the federal reserve board in the United States. Today, interest rates are one of the important tools for macroeconomic regulation. Japan's industrial standard, JISK 0101, defines a car as a vehicle equipped with an engine and a control device that can still drive on land without a fixed orbit or overhead line. The API data also showed that us crude imports last week fell by 138,000 barrels/solstice7100,000 BPD. Michael Zezas, an analyst at Morgan Stanley, also said the tax legislation would be a boon to the market in the short term, but may not be able to make fundamental changes. The current flattening of the us Treasury yield curve shows that the medium-term slowdown in the us economy and the recession of 2019 are not going away. A tax reform would widen the fiscal deficit, possibly in the future and exacerbate cyclical risks in the economy.