She really regretted to have carelessly given 10 dollars more back to the customer ,for she was fired by the supermarket nowregret to do 是遗憾地去做某事吧 - -！你说的没错,那是regret to do、regret doing的区别 ，我理解的是一种句式'to have done '表示她在遗憾已经做过的某件事