过境

该内陆跨国客运列车在途径第三国铁路干线过境时，海关人员上车进行了严格的查验。

gāi nèi lù kuà guó kè yùn liè chē zài tú jìng dì sān guó tiě lù gàn xiàn guò jìng shí, hǎi guān rén yuán shàng chē jìn xíng le yán gé de chá yàn.

When the inland cross-border passenger train was transiting through a third country's main railway line, customs officers boarded the train and conducted strict inspections.