The instruments by which imports are restricted are also somewhat different from and less transparent than traditional import tariffs, and are called non-tariff barriers (NTBs).

该仪器由进口限制也有所不同，那么透明，比传统的进口关税，并称为非关税壁垒（非关税壁垒）。

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Indeed, as conventional trade barriers, such as tariffs and import quotas, have come down over the past half-century, others, such as discriminatory regulations, have sprung up to take their place.

ECONOMIST: A survey of world trade