【正确答案】Friedman held that money demand is relatively stable and money supply must be guaranteed stable, too, if there should be equilibrium between money demand and money supply. So Friedman opposed the management of the aggregate demand raised by Keynes and focused on the importance of money supply. 　　According to the Monetarist School, the core of economic policies is placed on monetary policy, which should be the only important wander-working among all economic policies. Without monetary policy, other economic policies can’t achieve their anticipated effect. 　　Friedman assumed that the best choice in controlling money supply was the "single rule" of monetary policy, i. e. , making it known to the public to adapt a fixed increasing rate of money supply, excluded other factors, such as interest rates, credit flow, excess reserves on a voluntary basis, and so on. So monetary policy should just take a certain money stock as the only decisive factor. In order to carry out the "single rule”, three problems should be solved; the first is how to define the scope of the aggregate money supply; the second is how to decide the increasing rate of money supply and the third is whether or not fluctuation of the increasing rate of money supply is allowed during a certain period, a year or a season. The solution to the above problems is as follows; firstly, M2 should be the scope of the aggregate money supply; secondly, the increasing rate of money supply should be suited to economic growth rate and thirdly, it couldn’t be changed at will when the increasing rate of money supply had been decided. If there is need for change of the increasing rate of money supply, it should be announced and the band of fluctuation should be as small as possible.