我后悔没有早点开始准备这次考试。

I ___regret not starting to prepare for this exam earlier.

我后悔没有早点开始准备考试。

I ___regret not starting to prepare for the exam earlier.

我们很遗憾地通知您，航班因天气原因取消了。

We ___regret to inform you that the flight has been canceled due to bad weather.