They failed to pass the exam last time, I regretted _______________.
A、to be not able to help
B、being unable to help
C、being not able to helping
D、not be able to help
【正确答案】：B
【题目解析】：regret to do 对将要做的事遗憾(未做)regret doing 对做过的事遗憾、后悔 (已做)这个事情已经发生了.C改成being not able to help就对了.