一现在完成时概念及用法：
1 表示过去发生或已经完成的动作对现在造成的影响或结果。
常和just（刚刚），already
（已经），yet（已经），never（从不），ever （曾经），before（以前），so far（到目前为止）等时间状语连用。
2 表示从过去某一时刻开始一直持续到现在的动作或状态，还有可能继续下去，常和for
或since引导的时间状语连用。
此时的动词必须是延续性动词。
构成：have/ has(助动词)+V过去分词
肯定句：主语+ have/ has+V过去分词+其他
否定句：主语+ have/ has+not+V过去分词+其他
一般疑问句：have/ has+主语+ +V过去分词+其他
肯定回答：Yes, 主语+ have/ has.
否定回答：No, 主语+ haven’t/ hasn’t.
3 常用标志词语
already, never, ever, just, before, so far, yet ,since+过去的时间点,for+一段时间等
already常用于肯定句；yet用于否定句和疑问句。
二常用句型结构辨析
（一）have/has been to / have / has gone to / have/ has been in 辨析：
⑴ have/ has been to + 地名“曾经去过某地” , 现在已经回到原地。
He has been to England twice．他曾经去过英国两次。
(现在已经不在英国了)
Have you ever been to the Great Wall？你到过长城吗?（现在已经不在长城上）
⑵have gone to + 地名“已经去某地了”，说话时该人不在现场。
He has gone to England。
他已去英国了。
(已经不在说话的地方，到达英国或者在去英国的路上)
⑶ have been in +地点待在某地，常与时间段搭配。
I have been in Shanghai for three years.
（二）since与for区别：
1）for其后只能接表示“一段时间”的名词性短语，可用于多种时态。
表示动作或状态持续的时间长短；
since其后接表示“时间点”的短语或从句（一般过去时）；也可以接“一段时间+ago”，常用于完成时态；还用于句型“It’s+时间段+since+一般过去时态的句子”。
表示过去某个时间发生并持续至说话时的动作或状态。
I’ve lived in this city for five years.
He usually sleeps for 12 hours every day.
We’ve studied here since 2009.
She has worked here for five years.
It’s two years since I came to China.
练习：用since 和for填空
1.Jim has been in Ireland last Monday.
2.Jill has been in Ireland three days.
3.His aunt has lived in Australia 15 days.
4.Mike has been ill a long time. He has been in hospital 0ctober.
2）for 与since引导的时间状语可以进行相互替换
My uncle has worked at this factory for five years.
=My uncle has worked at this factory since five years ago.
练习：
I have studied English for five years.----- I have studied
English .
（三）延续性动词与非延续性动词
延续性动词表示经过、经历；非延续性动词表示行为的结果，不能与表示一段时间的状语连用。
I’ve known him since then. 表经历
He has finished the work. 表结果
（1）延续性动词与非延续性动词的用法：
①非延续性动词与短暂性时间（点）连用
非延续性动词也被称为终止性动词、瞬间动词，表示不能延续的动作，这种动作发生后立即结束。
如：open, die, close, 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.
He joined the Army three years ago.
②非延续性动词可用于“It is/has been +时间段+since”句型
It is/has been three years since I bought the book.从我买这本书到现在3年了。
I began to study English three years ago.
It is since I study Enlish.
I moved to Changchun 5 years ago.
.
Lily finshed her homework 2 hours ago.
.
③延续性动词表示能够延续的动作，如：learn, work, stand, know, walk, keep, wait, watch, read, sleep, live, stay等。
延续性动词可以与表示时间段的状语for+段时间/since+时间点/since引导的从句（过去时）/since+段时间+ago等连用。
(2)非延续性动词与延续性动词之间的转换：
①非延续性动词转换为相应的延续性动词，用于现在完成时态，时间状语为for+段时间/since+时间点/since引导的从句（过去时）/since+段时间+ago
The old man died 4years ago.
=The old man has been dead for 4 years.
I borrowed the book 5 days ago.
=I have kept the book since 5days ago.
borrow-keep buy-have catch a cold-have a cold put on-wear get to know-know get to sleep-sleep
②非延续性动词转化为“be+ adj 、adv、prep、n”
begin/start-be on go out-be out get to/arrive in/reach-be in die-be dead open-be
open
leave- be away finish-be over fall ill-be ill get up- be up fall asleep-be asleep
join-be a member of go to school- be in school become-be make friends-be friends come/go-be+相应的介词短语
练习-同义句转换：
1 I bought the dictionary last year.
I have the dictionary one year.
2 The film began 5 minutes ago.
The film for 5 minutes.
3 His grandfather died 5 years ago.
His grandfather for 5 years.
4 His uncle left the city 2 hours ago.
His uncle the city 2 hours.
三现在完成时与一般过去时的区别：
(1)一般过去时表示过去发生的动作或存在的状态；现在完成时表示过去发生的某一动作对现在造成的影响或结果。
强调的是现在的情况。
I saw this film yesterday. I have seen this film.
(2)一般过去时时间状语：yesterday, last year, 时间+ago, in 1990, just now…
现在完成时时间状语：ever、never、yet、already、recently、so far…。