——Congratulate you on your birthday.祝贺你的生日!
——Thanks for your kindness.多谢你的好意!
congratulate的用法：
1.congratulate sb. for sth. 为某事像某人祝贺
He is to be congratulated for his success.
他将会由于取得的成就而受到祝贺.
2.congratulate sb. on...就…向某人表示祝贺
We congratulated him on having passed the exam.
我们祝贺他通过了考试.
3.congratulate that+从句
I should congratulate you that you resisted the temptation.
我应向你祝贺,你抗住了这种引诱.
题中是就你的生日向你祝贺,所以for改成on.