In a letter of invitation, some information is essential and some optional. Put a check in the box beside an item which you think is essential to make an effective letter of invitation. A. □ A. Occasion for the invitation B. □ B. Person to be contacted C. □ C. Date, time and location D. □ D. All of the guests invited E. □ E. Guests’ arrival time F. □ F. Reservation of a room G. □ G. A simple map