请问我该如何回复老板的英文邮件?

问题描述:

请问我该如何回复老板的英文邮件?
邀请老板参加一活动,老板回复说不能去,我该如何回复老板呢?
老板的邮件如下:
I regret that I have other engagement on that day.
Have a nice day for all the participants.

Thanks for your reply and looking forward next!