Question

改错：someone in the office had made a mistake, and the firm ((regretted to have casused))

改错题：
someone in the office had made a mistake, and the firm ((regretted to have casused)) the customer inconvenient.
为什么括号里的错了，请高人详细讲下 好吗

Answer 1

涉及到regret的用法：

1. regret doing sth.对某事感到后悔遗憾（已经发生的事）

2. regret to do sth.为要做的是感到后悔（动作未发生）

3. regret to have done将来完成时

4. regret having done:为做过的事感到后悔，抱歉

    

    

   综上可见动作已经发生，且发生在过去，应与第四种情况吻合，故错误。

   应改成regretted having accused.

Answer 2

regret to do sth.(加动词原形)