profit or nonprofit The car engine is in the design phase, and the fuel used for the compression ratio is set. The compression ratio is a very important structural parameter of the engine, which indicates the volume of the gas at the beginning of the piston at the beginning of compression and the volume ratio of the gas volume at the end of the piston. In terms of power and economy, compression ratio should be bigger and better. The compression ratio is high, the power is good, the heat efficiency is high, the vehicle acceleration, the top speed of the car will be improved accordingly. However, the compression ratio of the gasoline engine is not too large due to the performance of the cylinder material and the vibration of gasoline combustion. In short, a high compression ratio USES a high grade fuel oil. The higher the fuel mark, the slower the oil will burn, and the lower the combustion detonation, the higher the compression ratio of the engine. On the contrary, the low-grade fuel combustion rate is faster, the combustion explosion is large, the engine compression is lower. The development of automobile modeling was better aerodynamic design combined with seating comfort to be properly, in full consideration to the above two key problems, on the basis of efforts to develop new technology in the field of human body engineering, in order to design and make cars more perfect, more outstanding for the target. One day, the car cab will form a "glass cover" with beautiful curves. It is reflected in the geometry of the body, the round and the streamline. At that time, the paint of car colour will reflect soft feeling and transparent feeling in the bright-coloured, so will be more pleasing to the eye. On the basis of introducing marginal concepts and mathematical argumentation, neoclassical has established a formal "perfect" mathematical model for the neoclassical "laissez-faire order" : general equilibrium. The price is the most important independent variable in this model, which can also be called price mechanism. The process of achieving general equilibrium is also a process of social resources guiding the flow of prices, so the price mechanism regulates the allocation of social resources. In general, us interest rates fall and the dollar weakens. Us interest rates rise and dollar trends favour. A change in the price of U.S. Treasury bills, especially long-term Treasury bills, can help to predict the direction of the U.S. dollar. If investors think the us inflation is under the control, then under the existing Treasury bonds interest rate to attract, especially short-term Treasury bills, will attract investors, bond prices to rise. breakthrough, but said, the final agreement was established to minimize the trade barriers, and to provide enough time to implement change.