I am afraid [I regret] that I shall not be able to attend the party.

我恐怕不能参加这次聚会〔很遗憾，我不能参加这次聚会〕。

youdao

I am afraid [I regret] that I shall not be able to attend the party.

我恐怕不能参加这次聚会〔很遗憾，我不能参加这次聚会〕。

youdao