Writing (e-mail):

Dear Auntie Joan and Uncle Bill,

it was really kind of you to invite me to your

anniversary party next month, but I’m afraid

I won’t be able to go. I’ve got to go to Canada on a

business trip from 15th to 20th October, so I won’t be

here on 17th when you’re having the party. I’m really

sorry that I’m going to miss the celebration. 

I wish I could be there with you all.

 Have a lovely time, anyway. And congratulations 

an managing 50 years of marriage!

Lots of love,

Marc