before是什么时态的标志答:一、一般现在时:标志:always,usually,often,sometimes,every week(day,year,month…),once a week,on Sundays,结构:①be动词;②行为动词 二、一般过去时:标志:ago,yesterday,theday before yesterday,last week(year,night,month…),in 1989,just now,at the age of 5,one day,long long ...