1. Please excuse my late reply to your very friendly letter of March 1.

　　2. I hope you will forgive me for not having written you for so long.

　　3. I hope you will excuse me for not having replied to you until today.

　　4. I humbly apologize you for my delay in answering to your kind letter of May 5.

　　5. I have to (must) apologize you for not answering your letter in time.

　　6. I must ask you to kindly accept our excuses, late as they are.

　　（5）我们对您的关照，谨致谢意

　　1. We request you to accept our warmest thanks for the anticipated favour.

　　2. We thank you in advance for the anticipated favour.

　　（6）我们时刻不忘尽我们所能，为您服务，等。

　　1. We assure you of our best services at all times.

　　2. We shall spare no efforts in endeavouring to be of services to you.

　　3. We shall be pleased to be of service to you at all times.

　　（7）请原谅给您添了麻烦

　　1. We hope you will pardon us for troubling you.

　　2. We regret the trouble we are causing you.

　　3. I regret the trouble it caused you.

　　4. We trust you will excuse us for this inconvenience.

　　5. We wish to crave your kind forbearance for this trouble.

　　6. We solicit your forbearance for such an annoyance.

　　7. We trust you will overlook this botheration, which we exceedingly regret.

　　8. Kindly excuse me for troubling you in this matter.

　　（8）请宽恕某某事项

　　1. Please excuse this clerical error.

　　2. We tender you our apology for the inconvenience this error may have caused you.

　　3. We request you to accept our regret for the error of our clerk.

　　4. We greatly regret that we have caused you such a inconvenience.

　　5. We wish to express our regret for the annoyance this mistake has caused you.

　　6. We frankly admit we were at fault and we are anxious to repair the consequences.

　　（来源：新浪教育论坛）