xiǎo xīn
小心火烛
xiǎoxīn huǒzhú
Be careful with fire/candles; beware of fire
路上很滑，一不小心就会跌跤。
lùshang hěn huá, yī bù xiǎoxīn jiù huì diējiāo
The road is very slippery, you'll fall if you're not careful
他做事一向很小心。
tā zuòshì yīxiàng hěn xiǎoxīn
He has always been very careful in his work