我收到了州税务部门关于新的通勤税的来信。

I got a letter from the state tax department ___concerning the new commuter tax.

我写信是为了回复您关于我所获奖品的来信。

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.