xiào lǐ cáng dāo
literally:
to hide a dagger behind a smile.
meaning:
very treacherous; nasty-nice
Example:
世界上有多少人被他們的甜言蜜語所蒙蔽，而不知道他們笑裡藏刀的厲害。
shì jiè shàng yǒu duō shăo rén bèi tā men de tián yán mì yŭ suǒ méng bì ，ér bù zhī dào tā mén xiào lǐ cáng dāo de lì hài 。
Quite a number of people have been fooled by the honeyed words, failing to see that they hid a dagger behind their smiles.
當心這位新的經理。他看起來很有禮貌，却可能是笑裡藏刀的那種人。
dāng xīn zhè wèi xīn de jīng lǐ ，tā kàn qǐ lái hěn yǒu lǐ mào ，què kě néng shì xiào lǐ cáng dāo 。
Beware of the new manage. He seems polite, but he might hid a dagger behind his smiles.
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