Represents描述Define定义Demonstrate论证Topic 1AOpportunity cost机会成本The highest-valued alternative that we give up to get something ⇒the opportunity cost of the activity chosen.我們为了得到一些東西而放弃的E xplicit cost显性成本 is a cost that involves actually laying out money.花钱I mplicit cost隐性成本 does not require an outlay of money; it is measured by the value, in dollar terms, of the benefits that are forgone. 非实质性Marginal Benefit边际收益指如果再多销售一单位的产品将会得到的收益，或目前最后卖出的一单位的产品所得到的收益。
边际收益在实现利润最大化中是一个非常重要的经济量，一般认为当边际收益等于边际成本时企业达到利润最大化Marginal Cost边际成本is the change in the total cost that arises when the quantity produced has an increment by unit.指的是每一单位新增生产的产品（或者购买的产品）带来的总成本的增量MC > MR ⇒an incentive to do less of that activity少刺激消费活动MB> MC ⇒an incentive to do more of that activity多刺激消费活动Production Possibilities Frontier PPF生产可能性边界is a graph representing production tradeoffs of an economy given fixed resources(假设、概念、图、移动）用来表示经济社会在既定资源和技术条件下所能生产的各种商品最大数量的组合，反映了资源稀缺性与选择性的经济学特征Topic 2ALaw of demand需求法则Other things remaining the same, the higher the price of a good/service, the smaller is the quantity demanded.假设其他因素不变，当一物品价格增加，其需求量会下降Law of supply 供给法则Other things remaining the same, the higher the price of a good/service, the greater is the quantity supplied.假设其他因素不变，当一件物品的相对价格上升时，其供给量会上升Equilibrium 平衡It means no shortage or surplus in the market.市场中没有短缺或过剩平衡点Factors that bring changes in demand.使需求变化的因素Income，Climate[水土,气候]，Age of the people，T echnology，Price of substitutes[替代品]，Advertising，Prices of related goods ，Expected future prices，Expected future income，Preferences[偏好]，PopulationFactors that bring changes in supply.使供给变化的因素。
Climate[水土,气候]，Technology，Expectations of producers[生产者期望]，Expected future prices，The number of suppliers，Prices of the factors of productionShifts in demand curve and shifts in supply cu rve需求曲线的变动和供给曲线的变动Substitutes and Complements替代品和互补品Diminishing Marginal Returns边际效用递减规律is the decrease in the marginal (incremental) output ofa production process as the amount of a single factor of production is incrementally increased, while the amounts of all other factors of production stay constant.指在投入生产要素后，每单位生产要素所能提供的产量增加发生递减的现象。
消费者剩余（Consumer Surplus）是指购买者的支付意愿减去购买者的实际支付量。
Topic 2BPrice Elasticity of Demand需求价格弹性measures the responsiveness of the quantity demanded to a change in price.衡量需求的数量随商品的价格的变动而变动的情况。
Price Elasticity of supply供给价格弹性measures the responsiveness of the quantity supplied to a change in price.指供给量相对价格变化作出的反应程度。
Elastic, Unit elastic, Inelastic, Perfectly elastic, Perfectly inelastic （根据弹性系数、图形判断）弹性、单位弹性、非弹性，完全具有弹性，完全无弹性（根据弹性系数、图形判断）需求价格弹性系数= 需求量变动的百分比/ 价格变动的百分比。
设：Q 表示一种商品的需求量；P 表示该商品的价格；DQ表示需求量变动值；DP表示价格变动的数值；Ed表示价格弹性系数，则：Ed=(△Q/Q)/(△P/P）弹性与价格、收益的关系※一般降价促销的商品都是需求弹性大于1的,如手机,服装,奢侈品;生活必备品一般是弹性小于1的,如食盐。
生活必需品的需求的价格弹性较小，非必需品的需求的价格弹性较大恩格尔定律(Engel's law) is an observation in economics stating that as income rises, the proportion of income spent on food falls, even if actual expenditure on food rise.一个家庭收入越少，家庭收入中（或总支出中）用来购买食物的支出所占的比例就越大。
Topic 3Characteristics of each market structures每个市场结构特征Perfect competition（完全竞争）: demand curve需求曲线、Short-run Decision短期决策是指企业为有效地组织现在的生产经营活动，合理利润经济资源，以期在不远的将来取得最佳的经济效益而进行的决策Long-run Decision长期决策Perfect competitive market 完全自由竞争市场①买卖众多Many buyers and sellers.②产品同质All firm selling identical products.③进出自由No barriers to new firmsentering the market. ④Sellers and buyers are well informed about prices Perfect information信息完全②Monopoly 垄断①One supplier ②Produces a good or service for which there are no close substitutes③High barriers to entry ④Firm is a price makerMonopolistic Competition 垄断竞争①Features of both competition and monopoly ②A large number of firms.③Each firm produces a differentiated product.④Product Differentiation: Firms compete on product quality, price, marketing and branding. Monopolistic competitive firms seek to differentiate their products in any one, or a combinationOligopoly 寡头①High barriers to entry ②A small number of firms ③Firms are price makers④Interdependency ⑤Temptation to cooperate/collude, to increase joint profit.opportunity cost：机会成本，需考虑sunk cost：沉没成本，不受决策影响的成本，表现为过去已经支付费用或根据过去的决策将来必须支付的费用。
Fixed cost：固定成本，不随产量变化而变化Variable cost：可变成本，随产量增加而增加※长期中，没有固定成本与可变成本之分Shut-down point停止营业点ØThe firm is indifferent between producing and shutting down temporarily.ØThe output and price at which the firm just covers its TVC.ØP=A VC is at its minimum.ØMC curve cuts A VC curve.ØIt incurs a loss equal to TFC.Monopoly(垄断):三级价格歧视Price Discrimination价格歧视一级价格歧视：为每单位产品制定不同的销售价格二级价格歧视：垄断厂商根据不同的购买数量确立的价格三级价格歧视：厂商对同一产品在不同的市场上对不同的消费群体收取弹性价格。