我最近都在忙于完成这项任务，所以很抱歉不能参加你的聚会。

I have been occupied in finishing this task recently, so sorry I can't go to your party.

youdao

我从上周开始就感觉不适，所以很抱歉我不能参加你的聚会。

I've been feeling ill since last week, so I am sorry that I can't go to your party.

youdao

他很抱歉地对我说他不能来参加这个聚会了。

He told me with regret that he could not come to the party.

youdao