the-present-perfect-continuous-tense-

[视频作者] Love203

[视频时长] 1:49

[视频类型] 校园学习

www.51voa.com/Everyday_Grammar_TV This video is relayed to you so that you can learn something about the use of the present perfect countious tense, which is meant to stress the duration of somthing uncompleted so far, something starting in the past a