DearAnne,
Thankyouforyourinvitationtodinneratyourhometomorrowevening.Unfortunately,itismuchtomyregretthatIcannotjoinyouandyourfamily,becauseIwillbefullyoccupiedthenforanimportantexamcomingthedayaftertomorrow.
Ifeelterriblysorryformissingthechanceofsuchahappyget-together,andIhopethatallofyouenjoyagoodtime.Isitpossibleforyouandmetohaveaprivatemeetingafterward?
Ifso,pleasedon’thesitatetodropmealineaboutyourpreferabledate.Idolongforapleasantchatwithyou.
Pleaseallowmetosaysorryagain.