to having been doing 和having been doing 的区别还有he went to the front_英语解答

to having been doing 和having been doing 的区别
还有he went to the front door,his son following hin里的following 的语法解释,

人气：133 ℃　时间：2020-05-11 18:14:06

解答

前一个是即将做,还没做.而后一个是做过了的意思.这种语法现象适用于各种地方