单词perfect-progressive
网络: 完成进行式；过去完成进行；完成进行态
The "present perfect progressive" is made with have been followed by an -ing form.
havebeen后面跟动词-ing形式，构成‘现在完成进行时’
Simple present perfect and present perfect progressive tenses
一般现在完成时和现在完成进行时
Simple past perfect and past perfect progressive tenses
一般过去完成时和过去完成进行时