Money supply is determined by the central bank of exogenous variables, the demand for money depends on the liquidity preference of people, when people's liquidity preference to enhance tend to increase the money hold, so rates are determined by the liquidity preference in joint decision currency demand and currency supply; Loanable ZiJinLun combines the first two interest rate determinism, that interest rate is determined by the supply and demand of loanable funds, including the total savings and new bank money supply and demand including the total investment and new currency demand, interest rate decision depends on common commodity market and money market equilibrium A car that has been modified to transport specialized goods.