唇齿

chún chǐ zhī guó

唇齿之国

close neighbour

hǎo sì chún chǐ

好似唇齿

be like the lips and teeth to each other

chún chǐ bān yī cún

唇齿般依存

mutually dependent

zhōng guó tóng běi hán de guān xi shì zhù míng de chún chǐ xiāng yī de guān xi

中国同北韩的关系，是著名的“唇齿相依”的关系。

China's relationship, famously "as close as lips and teeth", with North Korea.