Correct
钻心
/ zuānxīn /
Strokes
Definition
to sneak in/to infiltrate/to be piercingly painful/to be unbearable (of pain, itch etc)
Example
As an Adjective
(of pain, itching, etc) unbearable
1
Yǎng
痒
de
得
zuānxīn
钻心
feel so itchy that one can hardly stand still
2
Téng
疼
de
得
zuānxīn
钻心
feel unbearable pain
As a Verb
sneak in; infiltrate
3
Zuānxīn
钻心
zhànshù
战术
the tactic of taking the fortress from within