Correct

未曾

/ wèicéng / 
Strokes

Definition

hasn't (or haven't)/hasn't ever

Example

As an Adverb

not; did not; never

1
Shǔjià
暑假
qījiān
期间
  
,
wǒ
我
wèicéng
未曾
xiūxi
休息
guò
过
yī
一
tiān
天
  
。

I have not had even one day off for the whole summer vacation.

2
Wèicéng
未曾
kāifā
开发
de
的
zìránzīyuán
自然资源

undeveloped natural resources

3
Wèicéng
未曾
móumiàn
谋面

have never seen each other before