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". ^ h h, however, interest rates are still significantly lower than in November 2015, when an average of 2.62 PC. According to the length, there are mini passenger cars (no more than 3.5 meters), small passenger cars (3.5-7 meters), medium-sized buses (7-10 meters) and large passenger cars (more than 10 meters).