Supply and demand
供给的意义为供给方生产商品提供出售给需求方，需求的意义是需求方购买商品的货币多少。
供给包括生产过程与销售过程，生产过程对应生产供给量，销售过程销售供给量。
需求体现为需求曲线，需求曲线上某一点价格与数量之积是点需求，所有点需求的集合是线需求。
市场供求与价格的关系，销售供给量与需求决定价格，价格影响生产供给量。
双语使用场景
The brain needs a continuous supply of blood.───大脑需要不断供给血液.
The supply is inadequate to meet the demand.───供不应求.
An electric power company monopolises the power supply in this area.───一家电力公司垄断了该地区的电力供应.
That boy has eaten through a week's supply in a day!───这小伙子一天就吃光了一个星期的食品!
These goods are in short supply.───这些货物供应紧张.
Supply is conditioned by production.───供应受生产制约.
Nowadays that sort of innocence is in short supply.───现在那种天真烂漫很少见。
We pasted the enemy's greatest source of supply.───我们对敌人的最大补给来源予以重击.
穿跑鞋的公主
