9、Prices determine how resources are to be used.They are also the means by which products and services that are in limited supply are rationed(定量配给)among buyers.The price system of the United States is a complex network composed of the prices of all the products bought and sold in the economy as well as those of a variety of services， including labor， professional， transportation， and public services.The interrelationships(相互关系)of all these prices make up the “system” of prices.The price of any particular product or service is linked to a broad， complicated system of prices in which everything seems to depend more or less upon everything else.