(proverb)people can't change their basic nature(谚)本性难移
柯林斯高阶英汉双解学习词典释义
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A leopard is a type of large, wild cat. Leopards have yellow fur and black spots, and live in Africa and Asia.
PHRASE
本性难移；陋习难改
If you say that a leopard cannot change its spots, you mean that people or things are not able to change their basic characteristics, especially when you are critical of those characteristics.