When the government sets a maximum price for a specific good or service, that's a price ceiling.

政府为某一特定商品或服务设定的最高价格就是价格上限。

Assume the equilibrium price for gas is 3 dollars and the government sets a price ceiling here at only 1 dollars.

假设汽油的均衡价格是3美元，而政府为它设定的价格上限仅为1美元。