regret doing与regret having done有什么区别呢？谢谢！！！

Regret to do sth 与Regret doing sth有什么区别? regret to do/doing regret to do和regret doing有何区别 regret的词组是doing 还是to to 还是to have done...... I never regret doing anything !这句话语法有没有错，怎么翻译？ you're most likely incapable of doing so. They're in the classroom doing thier homework.为什么要用doing ,能否用do? must be doing 与 must have been doing 一道英语问题:one doing与one's doing keep doing 与keep on doing有什么区别?