Quotas or quantitative restrictions are the most common form of

Quotas or quantitative restrictions are the most common form of non-tariff barriers. A quota limits the imports or exports of a commodity during a given period of time. The limits may be in quantity or value terms, and quotas may be on a country basis or global basis.
【正确答案】：配额或数量限制是非关税壁垒最常见的一种形式。配额在一定时期内限制一种商品的进出口。这种限制可以以数量计算,也可以以价值计算;配额可以是针对国家的或者是全球性的。