因为根据WTO规则，同样的进口关税必须适用于所有WTO参与者 — — 这意味着，如果英国向欧盟的出口商品提供免税待遇，也就必须对来自世界其他地区的出口商品一视同仁。
Under the rules of the World Trade Organization, the same import duties must be applied to all WTO participants – which means that if Britain’s imports from the EU are duty-free, its imports from the rest of the world must be, too.