What have you done?to his/her
Dear Li,
I'm sorry that I have to write you this note.And the purpose of writing this is because I've accidentally damaged your painting.
Please accept my apology.I really did not mean to poured water on your painting.If teacher asks you,you just tell him the truth.
Sincerely Yours,
Your roommate
对不起,我写这字条给你的目的是因为我不小心损坏了你的画.
请接受我的道歉.我真的不是故意把水倒在你的画上.如果老师问你,你就直接告诉他吧.