Both men genuinely regretted ____.

问题描述:

Both men genuinely regretted ____.
(b) to have to leave
(c) having to leave
请问这两个中 为什么B 不可以?

b
regret to do sth 后悔去做某事,还未做.
regret doing sth 后悔做过某事 做过了.如果课文中是both men were genuinely sorry that they had to leave.那这个是,要离开,还是离开了??当然是要离开了。