customs

You must declare any goods over the duty-free limit at customs.任何超过免税额度的商品，你都必须在海关申报。

Customs officers searched the luggage thoroughly after the sniffer dog alerted them to one particular case.在嗅探犬对其中一个特定的箱子发出警报后，海关人员彻底搜查了行李。