(1)当现在完成时表示动作或状态从过去一直持续到现在时,常与for或since引导的时间状语连用。其结构为:“for+一段时间”;“since+一个过去的时间点”。如:
①I've studied English for three years.我学习英语已经三年了。
②I've studied English since three years ago.我三年前就学习英语了。
③I've studied English since I was ten years old.我十岁的时候就学习英语了。
(2)现在完成时态中延续性动词与非延续性动词的转换:
1)非延续性动词也被称为终止性动词、瞬间性动词,表示不能延续的动作,这种动作发生后立即结束。如:open, close, leave, die, become, begin, finish, come, go, move, borrow, lend, buy等。非延续性动词在肯定句中与表示时间点的状语连用,如:two years ago, at 5 o'clock。如:
He died 5 years ago.他5年前去世了。
3)延续性动词表示能够延续的动作,如:learn, work, stand, lie, know, walk, keep, wait, watch等。延续性动词可以和表示时间段的状语连用,如:“for+时间段”,“since+时间点”,“since+从句(过去时)”,“since+一段时间+ago”等,可用how long对持续时间进行提问。如:
①He has been dead since five years ago.=He has been dead for five years.=He died five years ago.他死了5年了。/他5年前死的。
②He borrowed the book two weeks ago.=He has kept the book for two weeks.=He has kept the book since two weeks ago.这本书他是两星期前借的。/这本书他借了两星期了。
③They left here three days ago.=They have been away from here for three days.=They have been away from here since three days ago.他们是3天前离开这儿的。/他们离开这儿3天了。
(4)另外还可以用“It's / It has been+一段时间+since引导的时间状语”,来表示动作的持续。如:
①It's three years since he came to this school.他来这所学校有三年了。
②It has been many years since we met last time.自从我们上次见面已经有好多年了。