Dear Mr. Smith，Thank you for your kind letter inviting me go andstay several days with you. But I'm terrible sorry to saythat I can't go this summer vacation， for I promisedto go and spend the holidays with my grandma， who live in the countryside.I'd like to tell you that I get on well with my study.And I must own the success in my English for yourhelp.At present I'm busy all day prepare for theexaminations and I feel sure I'll success.I do hope we can meet with each other soon.With best regard to you and Tom. Sincerely yours Jack