● 认为对方收到了自己的信件

几个月前，我们曾就……事给您写了一封信。
Some months ago we wrote you regarding... *regarding “关于……”。

就……事我们至今没有得到您的回音。
So far, we do not seem to have received word from you... *催促什么事情时。

如果在1998年12月1日前还得不到您的回音的话，……
If we do not hear from you by December 1, 1998...*语气有些严厉。

有关……事，我们还未收到您的任何回音。
So far, we have not received word from you... *so far “至今为止”。
So far, we have not received any word from you...

● 因回复迟了而表示歉意

很抱歉未能尽早给您回信。
We apologize for not replying to you earlier.

未能及时给您回信，我们深表歉意。
We are sorry for not answering your letter sooner.
We are sorry for not replying to your letter sooner.
We are sorry for not responding to your letter sooner.

久未回信，让您久等了。
Thank you for your patience. *patience “忍耐，耐心，耐性”。