有没有happen to doing?

有没有happen to doing? happen to be doing happen to do or happen doing? whatever happen to doing啥意思 happen to dohappen to be doing happen to have done翻译下,还有没有其他的词语也能这样用,这种用法叫什么名字,再多举些例子 happen to do和happen to be doing 的区别?顺便分别解释下.我问的是happen to be doing 不是happen to doing~ happen to do和happen to be doing有什么区别?区别是?HAPPEN TO BE DOING加的是进行时是吗?那是不是不能加结束性动词（短暂动词）了 有没有put forward to doing? 有没有 go back to doing sth? 有没有not dare to doing happen to 未发生 happen to be doing 正在发生 happen to hhappen to 未发生happen to be doing 正在发生happen to have done 已发生是这样区别的吗?老师说是.有点不确定 问个关于happen的用法的问题.happen.不是happen to do sth.那么 碰巧去做,碰巧正做,和碰巧已做.是不是分别是happen to do,happen to doing,happen to have been? happen on 和 happen to 有什么区别正确. enjoy doing 与enjoy to do区别有没有enjoy doing(我记得是没有) be look forward to doing这个对不对有没有这个 有没有is said to have been doing的结构 有没有prefer doing to do这种用法 be used to doing 有没有被动语态和现在完成时