HSK C5/V5
Correct

咳

/ hāi / 
Strokes

Definition

sound of sighing/(interjection expressing surprise, sorrow, regret, disappointment etc) oh/damn/wow

Example

As an Interjection
[audible sign of greeting or warning]
1
Hāi
咳
  
,
dàjiā
大家
kuài
快
lái
来
ya
呀
  
!

Hey, come here!

As an Interjection
[emphatic expression of surprise, regret or sadness]
2
Hāi
咳
  
,
zhēn
真
yǒu
有
zhèyàng
这样
de
的
guàishì
怪事
ma
吗
  
?

What? That's really absurd!

3
Hāi
咳
  
,
wǒ
我
jìngrán
竟然
zhème
这么
hútu
糊涂
  
!

Damn it! How stupid I was.

4
Hāi
咳
  
,
biètí
别提
lā
啦
  
!
Quán
全
guài
怪
wǒ
我
bùhǎo
不好
  
。

Oh, please don't say anything more about it. I am to blame.