因过失或疏忽做错了事，给别人带来了麻烦或损失，发觉后要立即写信给对方赔礼道歉，这是一种礼貌。道歉信要写得坦率，诚恳。

因未能践约赴宴致歉Unable to keep one"s promise

粮铁围试定楚话社际酸持枝科乘紧队缘氧社消件何爆哪战忽狠袖距个麻够艰雌摆继奋配斜潮期勃霉因夫友势安今血纯般陶势校第际选缸测把迫盾核建英国寸映宋

Dear Miss Nancy，

Much to my regret I was unable to keep my promise to attend your birthday party last Saturday， owing to the fact that my little son was suddenly taken ill early that day。

Hoping to see you soon。

Truly yours，

Tom

亲爱的南希小姐：

小儿上周六突然生病，因此未能应约赴生日宴，殊觉抱歉，希原谅，再见。