HSK 3
Zhè jiàn shì nǐ yídìng yào bǎomì.
You must keep this matter secret.
HSK 4
Tā duì zìjǐ de gōngzuò nèiróng hěn bǎomì.
He's very secretive about his work.
HSK 5
Zhè shì bǎomì wénjiàn, bùnéng wàichuán.
This is a confidential document, it cannot be shared.
