顺手采纳答案
一、 一般现在时：
1.概念：经常、反复发生的动作或行为及现在的某种状况.
2.时间状语：always,usually,often,sometimes,every week (day,year,month…),once a week,on Sundays,
3.基本结构：动词 原形 （如主语为第三人称单数,动词上要改为第三人称单数形式）
4.否定形式：am/is/are+not;此时态的
谓语动词若为行为动词,则在其前加don't,如主语为第三人称单数,则用doesn't,同时还原行为动词.
5.
一般疑问句：把
be动词放于句首；用
助动词do提问,如主语为第三人称单数,则用does,同时,还原行为动词.
6.例句：.It seldom snows here.
He is always ready to help others.
Action speaks louder than words.
二、 一般过去时：
1.概念：过去某个时间里发生的动作或状态；过去习惯性、经常性的动作、行为.
2.时间状语：ago,yesterday,the day before yesterday,last week,last(year,night,month…),in 1989,just now,at the age of 5,
one day,long long ago,once upon a time,etc.
3.基本结构：be动词；行为动词 的
过去式4.否定形式：was/were+not;在行为动词前加didn't,同时还原行为动词.
5.一般疑问句：was或were放于句首；用助动词do的过去式did 提问,同时还原行为动词.
6.例句：She often came to help us in those days.
I didn't know you were so busy
三、 现在完成时：
1.概念：过去发生或已经完成的动作对现在造成的影响或结果,或从过去已经开始,持续到现在的动作或状态.
2.时间状语：recently,lately,since…for…,in the past few years,etc.
3.基本结构：have/has + done
4.否定形式：have/has + not +done.
5.一般疑问句：have或has.
6.例句：I've written an article.
The countryside has changed a lot in the past few years.