一封感谢信（英语）

Dear schoolmate,

I don’t know whoyou are, but I am really grateful to you. Yesterday, I lost my library card inthe playground. I didn’t realize it until I got home after class. I was soupset, because it’s too bothersome to register another one. But today, when I gotto school, the guard told me that someone picked my library card and gave it tohim. I was so exciting to hear the news. You did not leave your name and I don’tknow who you are. I am really appreciated for what you did.

Yours

Kelly