Please accept our sincere regrets.

请接受我们诚挚的歉意。

youdao

Please accept my sincere regrets for not being able to join...

我不能参加……了，请接受我真诚的歉意。

youdao

If you must decline at the last minute, please notify the host prior to the event or first thing the next day with sincere regrets.

如果你最后还是要拒绝邀请，记得在活动前通知主办人，并且事后第二天马上至上诚挚的歉意。

youdao

"We are very disappointed with the outcome of the launch and offer our sincere regrets to our customer, Intelsat, and their spacecraft provider, Boeing, " Kjell Karlsen, president of Sea Launch AG, said in a statement.

BBC: Science & Environment