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