Dear mum,
I am writing this letter to apology to you for forgetting your birthday yesterday.As you know, I am quite busy preparing for my English examination this term recently. However, I bought a gift for you this morning and I put it on the desk.Dear mum, I wish you could like it and have a good mood. Happy birthday,mum! I love you!
I am terribly sorry to give you present today.
Yours sincerely,
Tom