双方私下达成的谅解不能取代正式合同。Shuāngfāng sīxià dáchéng de liàngjiě bù néng qǔdài zhèngshì hétóng.The understanding the two sides reached privately cannot replace a formal contract.
他私下找我谈话,劝我不要辞职。Tā sīxià zhǎo wǒ tánhuà, quàn wǒ búyào cízhí.He talked to me privately, urging me not to quit my job.
有意见可以当面提,别私下议论别人。Yǒu yìjiàn kěyǐ dāngmiàn tí, bié sīxià yìlùn biérén.If you have concerns, raise them to someone's face; don't gossip about others in private.