Correct
老大难
/ lǎodà nán /
Strokes
Definition
old trouble
Example
As an Adjective
(of a problem) complicated, knotty and long-pending
1
Lǎodànán
老大难
wèntí
问题
knotty and long-pending problem
2
Lǎodànán
老大难
ànjiàn
案件
difficult and pending case
As a Noun
organization/enterprise with knotty and long-standing problems; well-known trouble-making organization
3
Zǔzhuāng
组装
chējiān
车间
shì
是
gè
个
lǎodànán
老大难
。
The problem in the assembly workshop is knotty and long-pending.