构成:have been doing sth. 用法:表示从过去某一时间开始一直延续到现在的动作。这个动作可能刚刚结束,也可能仍在继续,并可能延续到将来。(表示到现在为止一直在发生或反复进行的动作) ––– How long have you been waiting here? ––– I have been waiting here ...