Economics 急!!

1 The opportunity cost may be many.
Example 1: The expenditure on medical carefor the poor may be decreased. Poor people do not afford to pay high medical fee and their health become worse.
Example 2: The expenditure on high education may be dedcreased. poor students cannotpay university fees.

2 It depends. Usually a present is understood to be a free gift. It would be meaningless if the receipant has to pay the giver any monetary reward. But sometimes the receipant may have to pay extra cost when using the gift, for example, he gets a gift of a house but need to pay to re-decorate the house.

Economics is the social science that studies the production, distribution, and consumption of goods and services. The term economics comes from the Greek for oikos (house) and nomos (custom or law), hence "rules of the house(hold)."

A definition that captures much of modern economics is that of Lionel Robbins in a 1932 essay: "the science which studies human behaviour as a relationship between ends and scarce means which have alternative uses." Scarcity means that available resources are insufficient to satisfy all wants and needs. Absent scarcity and alternative uses of available resources, there is no economic problem. The subject thus defined involves the study of choices as they are affected by incentives and resources.


Areas of economics may be divided or classified in various ways, including:

microeconomics and macroeconomics
positive economics ("what is") and normative economics ("what ought to be")
mainstream economics and heterodox economics
fields and broader categories within economics.
One of the uses of economics is to explain how economies work and what the relations are between economic players (agents) in the larger society. Methods of economic analysis have been increasingly applied to fields that involve people (officials included) making choices in a social context, such as crime [3], education [4], the family, health, law, politics, religion [5], social institutions, and war [6].

A graph of World GDP over the last 2000 years. The study of GDP growth is a key area of macroeconomics.Macroeconomics examines the economy as a whole "top down" to explain broad aggregates and their interactions. Such aggregates include national income and output, the unemployment rate, and price inflation and subaggregates like total consumption and investment spending and their components. It also studies effects of monetary policy and fiscal policy. Since at least the 1960s, macroeconomics has been characterized by further integration as to micro-based modeling of sectors, including rationality of players, efficient use of market information, and imperfect competition.[1] This has addressed a long-standing concern about inconsistent developments of the same subject.[2] Analysis also considers factors affecting the long-term level and growth of national income within a country and across countries.