concerning

我们需要讨论关于项目截止日期的问题。

We need to discuss the issues ___concerning project deadlines.

我写此信是为了回复您关于我获奖的来信。

I am writing in reply to your letter ___concerning the prize I won.

我们需要就项目的未来进行一次严肃的讨论。

We need to have a serious discussion ___concerning the project's future.