Dear Grandmother,
I am writing this letter to inform you that I cannot visit you in the near time.
First of all, I want to say sorry for you my grandma because I was very busy in my university for a last month because of that I have no time to visiting you sooner and come to your home like my promise to you before. I had final exam in my university and after the exam my university made a farewell party. All of the student must be able to attend the party.
However, I will visit you in the next week. I promise I will come to see you and it will never change. I have bought my ticket plane so, you do not need to worry about my presence in your home. I hope you can understand about my reason which make you waiting for a long time.
Best Regards,
Anita
