in short supply

not easily obtainable; scarce

供应不足，短缺

he meant to go, but time and petrol were in short supply.

他想要走，但时间和汽油都不够了。

on supply

(of a schoolteacher) acting as a temporary substitute for another

（学校教师）代课

supply and demand

the amount of a good or service available and the desire of buyers for it, considered as factors regulating its price

（商品，服务的）供应与需求，供求

by the law of supply and demand the cost of health care will plummet.

根据供求关系定律，保健费用将会骤降。