Chapter 1. Ten Principles of Economics
1. how to define economics
    Economics studies how society allocate its scarce resources
2. How does individual make decisions?
   1) trade-off    2) opportunity cost 3) act to incentives 4) rational people compare marginal benefit against marginal cost
3. How does individual interact?  
  1) trade makes everyone better off  2) market is the place of economic activity  3) gorvernment can sometimes adjust market     outcomes
4. How economy works as a whole
  1) from a country level, the living standard of a country depends on its ability to produce; 2) prices rise if too much money printed;  3) a short-run trade-off between inflation and unemployment----Philips Curve. to decrease inflation may cause a temporary increase in unemployment