[, ] (usuallythe demand curve) () a line on a graph that shows the relationship between the price of a product or service and the quantity of it that people buy需求曲线（反映产品或服务的价格与购买量之间关系的曲线）◆Each point on the demand curve represents the quantity demanded at a particular price.需求曲线上的每个点代表某一特定价格的需求量。◆An increase in incomes caused a shift in the demand curve for automobiles.收入增加导致汽车需求曲线的变化。