There have been great changes in our city since he became the may_英语解答

There have been great changes in our city since he became the mayor(画线部分提问since.mayor)

人气：341 ℃　时间：2019-09-05 07:47:07

解答

正确答案是：How long have there been great changes in your city?
对时间状语for...和since.提问时,同样都用how long.