base nek !
-when the "kỉ niệm đang nhớ" happened ?
-you share your "kỉ niệm đang nhớ" with who ?
-why do you think that's a "kỉ niệm đang nhớ" ? Remember to write "Dear...." at the top of the letter
then at the end of the letter,you should write " I want to to know what is your "kỉ niệm đang nhớ" too ! So please write to me soon !" or "That's all,what about you ? Write to me soon !"