[生活美語]
Use these words and phrases to help you on any business/finance/economics related writing questions!

Supply (供應) and Demand (需求)The point where supply and demand meet = equilibrium point (均衡點)
If you look at the picture, you will see that there is excess demand (求過於供) for homework assignment since the P (price 價格) = 0.
In this graph, the demand for homework 需求量 (QD) = 14, but the supply of homework 供應量 (QS) = 2。
因此,當價格 = 0 時,需求量 > 供應量 ,這情況稱為「超額需求 (excess demand)」。這即是我們日常所說的供不應求。
Source and more basic econ info:
http://www.econman.net/Cert/F4/Demand/PriceDetermination.htm