customs frontier的用法和樣例：
例句
- VAT on self-used articles brought or mailed into China by individuals shall be levied together with Customs Duty.
個人攜帶或者郵寄進境自用物品的增值稅，連同關稅一并計征。 - They were shot when trying to cross the frontier illegally.
他們在企圖偷越國境時被擊斃。 - Sanitary supervision at frontier ports should be conducted under the direction of the health quarantine officials.
國境口岸衛生監督應在衛生檢疫官員的指導下進行。
