HSK V7-9
Correct

不亦乐乎

/ bù yì lè hū / 
Strokes

Definition

lit. isn't that a joy? (quote from Confucius)/fig. (jocularly) extremely/awfully

Example

Definition
isn't it a pleasure
1
Yǒu
有
péng
朋
zì
自
yuǎnfāng
远方
lái
来
  
,
bùyìlèhū
不亦乐乎
  
?

Is it not a pleasure when friends come from afar?

Definition
［used jocularly as a complement after得］extremely; awfully; terribly
2
Wèile
为了
dàjiā
大家
de
的
lìyì
利益
  
,
tā
他
zhěngtiān
整天
máng
忙
de
得
bùyìlèhū
不亦乐乎
  
。

For the interest of all of us, he is awfully busy rushing about all day long.

3
Jīdòng
激动
de
得
bùyìlèhū
不亦乐乎

be extremely excited