Civil servants should be incorruptible in their duty and not show favoritism.
Tips
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Formal and laudatory. Standard vocabulary in Party discipline contexts, civil-service training, and eulogies for officials. Rare in casual speech.
memory
廉洁 = 'incorruptible' + 奉公 = 'serve the public'. The two halves are modern stock phrases bolted together — learning the pair pays off beyond this idiom.