a thorn in one's side的用法和样例：
- He was a thorn in the police's side.
- He's been a thorn in my side ever since he joined this department.
- Camel dung!$ You are indeed a thorn in my side.
- His sister is a thorn in his flesh.
- It was to be a thorn in the side of the Dutch.
- He was a thorn in the police's flesh.