现在完成进行时(have/has been doing)：主要表示现在以前这一段时间里一直进行的一个动作，这个动作可能仍然在进行，也可能停止了。常用的时间状语有lately，recently，just，already，yet，up to now，till now，so far，to this day，in the past few years/months/weeks/days，over the past few years，during the last three months，for the last few centuries，through centuries，throughout history等。