over the past 12 months 和 at the past 12 months 有什么区别?

over the past是什么意思 over the past centuries over the past century意思 over the past 12 months 和 at the past 12 months 有什么区别? LOOKING BACK OVER THE PAST是什么意思 over the past ten years是什么意思 over the past year.这儿的 over the past centuries汉语意思 In study after study over the past Several times over the past decades over the past ten 为什么over可以用在这里? I can not forget the Over the past memory of the changes in Beijing over the past 100 为什么是in the past three years而不是over the past three years over the past twenty years 还是in the past twenty years in the past two years和over the past two years有什么区别? during the past 20 years 和 over the past 20 years一样吗? in the past 3 years 和 over the past 3 years的区别