The circular-flow diagram is an example of ______.
A、a laboratory experiment
B、an economic model
C、a mathematical model
D、All of the above are correct.
微观经济学（全英）
章节列表
1. General Overview of Economics282. Principles of Economics353. Circular-Flow Diagram and PPF204. Interdependence and Trade205. Demand and Supply756. Elasticity717. Price Control and Taxation408. CS, PS and the Efficiency of Markets109. Costs of Taxation2510. International Trade3011. Externalities3112. Public Goods and Common Resources2013. The Costs of Production20