知识点①:现在完成时
.一般现在时用法:
①过去发生的动作对现在造成的影响或结果:强调结果
     e.g. Yesterday I finished my homework, that’s to say, I have finished my homework now.
②过去已经开始一直持续到现在的动作或状态:强调继续
      e.g. I have lived here since 1990.
. 现在完成时的构成        have/has+过去分词
. 现在完成时的四个基本句型
       肯定句    He has finished the work.                  一般疑问句    Has he finished the work?
       否定句    He has not finished the work.            两回答    Yes ,he has. / No, he hasn’t.
       特殊疑问句    What has he done?     
. 在下列情形下用现在完成时
1九词语
already 已经       肯定句中或句尾   
e.g. I have already found my pen. = I have found my pen already.
yet已经      否定句和疑问句句尾   
e.g. I have not finished the work yet.
Have you bought a computer yet?
ever曾经    句中              e.g. Have you ever seen pandas?
never从不  句中              e.g. I have never been to Beijing.
just刚刚     句中            e.g.  I have just done my work.
before以前        句尾      I have never been there before.
so far到目前为止          e.g. So far he has learnt 200 words.
how long多久                 & How long have you lived here?
how many times多少次   e.g.How many times has he been to Beijing?
2两词组
       have<has>gone to去了某地   例:He has gone to Beijing   (去了北京)
       have<has>been to去过某地   例:He has been to Beijing.   (去过北京)
3两结构
for two months
for +一段时间
Jim has lived here for 2 months.
since last year
since +过去点时间
Lucy has been in Beijing since 3 years ago.
since 3 years ago
since 1990
since he came here
since +过去时态句子
He has been in China since he came here.
4如果句子里面没有时间状语,汉语意思能够加“已经”,往往用现在完成时态。
  & Have you lost your library book? 你已经弄丢了从图书馆借的那本书吗?
5现在完成时态还常常用于下列句型
   They have planted many trees in the last few years. 在过去的几年,他们已经种了很多树。
   This is the best book I have ever read. 这是我曾经读过的最好的一本书。
      It is the first time I have played the computer games. 这是我第一次玩电脑游戏。
. 在现在完成时中,一次性动词不能和一段时间状语连用
    & He has bought the book for 3 years.(错)
buy这个一次性动词不能和一段时间for 3 years连用, 改正的办法有五种:
        He has bought the book..                       (去掉一段时间for 3 years)
        He bought the book 3 years ago             (改为一般过去时,使句子的意思不变)
        It’s 3 years since he bought the book. = 3 years has passed since he bought the book.
                                                                      (改为固定句型 It is ---since---
        He has not bought the book for 3 years. (改为否定句)
        He has had the book for 3 years.            (用延续性动词have代替buy
.还有其他一次性动词也是这种情况,可参照前面的五种办法改正,前四种改法都一样,第五种改法各不相同,举例如下:
come/arrive/get to/reach  be here
       例:I have come here for 3 years.join的四种用法(错)        改为:I have been here for 3 years.
leave/go be away
       例:He has left for 3 hours.(错)           改为:He has been away for 3 hours.
begin/start be on
       例:The film has begun for 3 minutes.(错)          改为:The film has been on for 3 minutes.
open be open / close  be closed
       例:The shop has opened for 3 years.()        改为:The shop has been open for 3 years.
die be dead
       例:His father has died for 3 years.()            改为:His father has been dead for 3 years.
finish/end be over
       例:He has finished the work for 3 days.()           改为:The work has been over for 3 days
join            例:I have joined the army for 3 years.(错)
                            改为:I have been in the army for 3 years. I have been a soldier for 3 years.
buy /catch     have
e.g.  I have bought the bike for 3 years.(错)         改为:I have had the bike for 3 years.
    e.g. He has caught a cold for 3 days.(错)            改为:He has had a cold for 3 days.
borrow  keep
      e.g. I have borrowed the book for 3 years. (错)          改为:I have kept the book for 3 years.
还有其它的归纳如下:
break  be broken                    get up  be up
marry  be married                  become  be                         lose  be lost
. 延续性动词和终止性动词
①延续性动词:表示的动作是能延续的动作,这种动作可以延续下去或产生持久的影响。如:learn work stand lie know walk keep have wait watch sing read sleep live
②终止性动词:也叫非延续性动词,瞬间动词,一次性动词。表示的动作不能延续,即动作发生后立即结束,产生某种结果。在有了某种结果后,动作就不能再继续下去。
如:leave ,start, set out ,arrive ,reach ,get to, begin, stop, shut, turn off, marry ,put ,put on, get up, wake, fall, join ,meet, receive, finish, end, complete ,become, come, go, die, open, close, break, give, jump ,buy, borrow
. 终止性动词不能和一段时间状语连用。
     He has died for three days. (错,终止性动词die不能和一段时间for three days连用)