In the past several weeks,many cities in China have been suffeing from heavy fogs.
问题描述：
In the past several weeks,many cities in China have been suffeing from heavy fogs.
想问,in the past several weeks 不是一个过去时态的时间状语吗?为什么用现在完成时呢?
答
have been suffeing是现在完成进行时.In the past several weeks,是指过去的某个时刻一直延续到现在,所以用have been suffring,表示一直延续到现在,而且还在继续的状况.