scarcity exists when the quantity demanded for a good is gerater than quantity supplied atzero price. shortage exists when the quantity demanded for a good is greater than quantity supplied at aprevailing price.
另外發現#2有錯誤 shortage係唔夠goods去滿足wants(Qd>Qs) Shoratge arises when the quantity demanded of a good is greater than its quantity supplied at a price lower than the equilibrium price. 重點是DEMAND與WANTS的分別。