为什么over the years用现在完成时而it 's about changes in Beijing over

来源：学生作业帮编辑：搜搜做题作业网作业帮分类：英语作业时间：2024/06/01 18:46:13

为什么over the years用现在完成时而it 's about changes in Beijing over the past century不用呢

it=这篇文章
这篇文章现在是让看到它的读者了解过去的一个世纪中北京发生的变化.
也就是说it主语 's系动词 about changes表语 in Beijing over the past century定语,注意：定语中的内容影响不到前面句子的时态的.
再问：真的很谢谢

为什么over the years用现在完成时而it 's about changes in Beijing over The exhibition is about changes in Beijing over the past 100 the changes in Beijing over the past 100 It's over there?为什么用over? It's+been+in+Boston+for+over+250+years. Many changes()place over the years in Guangzhou.A.will take great changes have taken place over the past fifty years. It's over 900 years old. helen got 100 in her exam.she is over the moon about it中over In the past three years there great changes in Beijing. There______great changes in our hometown over the past 15 ye 为什么是in the past three years而不是over the past three years

为什么over the years用现在完成时 而it 's about changes in Beijing over