over last 50 years的意思?

over last 50 years的意思? 请问over the years 的意思 over four years ago的over什么意思 英文over the last two years in the last few years=over the years吗 英语翻译请帮忙翻译以下文章Over the last 50 years,America has experienced How has people’s leisure time changed over the last 50 years over the last two months这个时间状语中over的意思和用法? 英语翻译Over the last 30 years ,social scientists have conducted 英语翻译Over the last 30 years,social scientists have conducted Thanks to on-going automation over the last 10 years, over three years的同义词