once bitten twice shy的意思是：一回上当两回乖。
1.She certainly won't marry again once bitten, twice shy.
2.She certainly won't swim again-once bitten, twice shy.
3.Once bitten, twice shy. This means you never make the same mistake twice. You learn from your mistakes.
4.Once bitten, twice shy. I always do now.
5.I'm sure the shopkeeper gave me too little change so I am going to check it carefully next time - once bitten, twice shy.