一段时间+agolast+时间名词yesterday1. 概念：表示现阶段经常发生的动作或现在的某种状况，也表示客观事实、客观规律或客观真理。谓语动词要用原形，主语是第三人称时，谓语动词要用第三人称单数形式。2. 常见时间状语标志：always, often, sometimes, usually, every day, on Sundays, once a day / week / month等。例如：I do some exercise every day. 我每天做一些锻炼。She knows
yesterday, last week, an hour ago the other day, in 1982，just nowthis morning, tonight, this April,already, recently, lately ，agoonce upon a time ,last monday之类等等
