a thorn in one's flesh
眼中钉
A: The stepmother was very wicked.She couldn't stand a happy smile on the boy's face.
A:那个继母坏透了,她看那孩子笑一笑都难受。
B: And?
B:那怎么样?
A: And she did her best to pull out the thorn in her flesh and the boy lost whatever made him happy.
A:她想方设法除去她的眼中钉,那孩子生活中的快乐全没有了。
B: Poor child!
B:可怜的孩子!