【正确答案】Thank you for inviting us to the wonderful dinner to be held on Friday at the Guest House We would like to accept your warm invitation but we can not due to an earlier appointment.
Some days ago,we met our friend Li Ming, We were very happy,then he asked us to go to a pop music concert which was his favorite and we have consented.
Anyway we feel very sorry for disappointing you. Looking forward to seeing you then.
Yours sincerely,
Mr. &Mrs. Robert Li