HSK C3/W3/V4
Correct

曾

/ zēng / 
Strokes

Definition

once/already/ever (in the past)/former/previously/(past tense marker used before verb or clause)

Example

As an Adverb

once; formerly; sometime ago

1
Xiǎnéryìjiàn
显而易见
  
,
tā
他
yě
也
zēng
曾
fēngliútìtǎng
风流倜傥
guò
过
  
。

He had obviously been romantic once.

2
Jī
几
nián
年
qián
前
  
,
wǒ
我
zēng
曾
qù
去
guò
过
nàli
那里
yī
一
cì
次
  
。

I went there once a few years ago.