tariff-free environment如何翻译?

tariff-free environment如何翻译? 翻译across the international phone lines in tariff-free email packets tariff是什么意思 BTN Tariff number BTN Tariff number restrictive business tariff是什么意思 tariff code international compound tariff是什么意思 tariff classification是什么意思 ad valorem tariff是什么意思 the harmonised tariff code preferential tariff是什么意思 tariff-jumping怎么翻译 tariff jumping翻译, Free free free free