...类似语法知识点,个别动词用法,+doing,+to do,等等答:be busy doing sth.be worth doing spend time (in) doing sth.have difficult/trouble in doing sth have fun doing 3.介词后(on, in, of, about, at, with, without, for, from, up, by等)be good at doing sth.thank you for doing sth.give up doing sth.stop sb. from doing ...