Correct

猛不防

/ měng bù fáng /
Strokes

Definition

suddenly/unexpectedly/taken by surprise/at unawares

Example

As an Adverb

unexpectedly

1
Yǒurén
有人
měng
fáng
cóng
hēiyǐng
黑影
cuān
蹿
chūlái
出来
  
,
le
tiào
  

Someone came out of the dark unexpectedly and gave me quite a start.