1. 表示过去的动作对现在的影响或结果，常用recently, lately, ever, never, once, before, yet, just等作时间状语。
He hasn't heard any news from his son lately. 他最近没有得到他儿子的任何信息。
Have you ever been to London? 你曾去过伦敦呢？
2. 表示开始于过去某一时刻，一直持续到现在而且还有可能继续下去的动作。常用so farup till now, since, for a long time, in the past/last few years, these days等作时间状语。
So far no life has been found outside the earth.迄今为止，没有在地球外的星球上发现生命。
He has learned 5，000 English words since he went to college.自从他上大学以来已经学会了5,000英语单词。
“This/It is＋the ＋序数词＋time ＋that...”句式中，that后的从句用现在完成时。
This is the second time that I have visited the university.
这是我第二次参观这所大学。
非延续性动词的否定形式可以与表示延续时间的状语连用即动作不发生的状态是可以持续的。
I haven''t received his letter for almost a month.since与for用法比较
since 用来说明动作起始时间
for 用来说明动作延续时间长度
I have lived here for more than twenty years. 我在这里住了二十多年了。
I have lived here since I was born.. 我从出生起就住在这里。
My aunt has worked in a clinic since 1949. 我姑姑从1949年开始一直在一个小诊所工作。
误区提醒
并非有for 作为时间状语的句子都用现在完成时。
I worked here for more than twenty years. 我现在已不在这里工作。
I have worked here for many years. 现在我仍在这里工作。
1. 用于完成时的区别
延续动词表示经验、经历； 瞬间动词表示行为的结果，不能与表示段的时间状语连用。
He has completed the work. (表结果)
I''ve known him since then. (表经历)
2用于till / until从句的差异
延续动词用于肯定句，表示"做直到"； 瞬间动词用于否定句，表示"到，才"
He didn''t come back until ten o''clock.
直到十点钟他才回来。
He slept until ten o''clock.
他睡到了十点钟。
常见考法
1. 把考察放在从句中增加难度
2. 和被动语态放在一起考察；
3. 根据状语确定时态
4. 用现在完成时的句型
误区提醒
1. 现在完成和一般过去弄混；
2. 现在完成时的句型不熟悉；
3. 不能根据状语选定现在完成时。
1. You don’t need to describe her. I _______ her several times.
A. had met
B. have met
C. met
D. meet
2. —I’m sorry to keep you waiting.
—Oh, not at all. I _______ here only a few minutes.
A. have been
B. had been
C. was
D. will be
3. —Do you know our town at all?
—No, this is the first time I _______ here.
A. was
B. have been
C. came
D. am coming
【答案及解析】