对国家之间商品和劳务的自由交换实行的人为限制。最常见的贸易壁垒是关税、进口限额及外汇管制。一国之所以实行这种限制,是想使本国的生产者在国内市场上不受外国生产者的竞争,减少失业人 There are artificial restrictions on the free exchange of goods and services between countries. The most common trade barriers are tariffs, import quotas, and foreign exchange controls. The reason why such a restriction is imposed in a country is to prevent its producers from competing with foreign producers in the domestic market and reduce the number of unemployed people.