现在完成时表示1）过去发生或已经完成的动作或存在的状态对现在造成的影响或结果．（即它的＂完成用法＂）e.g. I have just cleaned the classroom.  2)过去已经开始，一直持续到现在的动作或状态。注意：此时动作可能还要继续。（即它的＂未完成用法＂）。 E.g. He has lived in Beijing for ten years.

    其结构是“have/has+过去分词”。过去分词的变化分规则与不规则两种。规则变化与过去式相同，不规则变化需要另记。

    它的否定句是在have/has后边加not，变一般疑问句是把have/has提前。E.g. I have ridden a horse.  I have not ridden a horse.  Have you ridden a horse?

    它的时间状语通常为already, just, yet, ever, never, before等。另外还可和since+表过去的时间点，for+时间段连用。

    做题时常见错误如下：

　　一、易丢掉have/has

　　例：He taken (take) the medicine before.

    答案：has taken

    解析：have/has 为助动词，起构成时态的作用，是不能省略的。我们可以这样记：

　　　“现在完成时态中，have/has 不可缺。”

　　二、have与has易用混

    例：I has never heard (hear) of that before.

    答案：have heard

    解析：现在完成时与一般现在时一样也有单三人称的变化，当单三人称作主语时用 has, 一般人称作主语时用have．

    三、延续性动词与短暂性动词易弄错

    例：She has left (离开) for 2 hours.

　  答案：has been away

    解析：在肯定句中，与since或for引出的时间状语连用的是延续性动词，不能是短暂性动词，但在否定句中短暂性动词也是可以的。E.g. I haven't bought clothes for one year. 在此题中leave是短暂性动词，不能与for+时间段连用，须把它改成相应的延续性动词。如stop be over等。此题中leave要改成be away。这两种词的转换是学习现在完成时需要注意的。

四、have been to与 have gone to 易弄混

    例：我去过北京。

    I have gone to Beijing.

    答案：I have been to Beijing.

    解析：'have been to+地点' 是表示曾去过某地，但此刻不在那儿（即在说话的地方）。而'have gone to+地点' 是表示去某地了，此刻在路上或已经到了那个地方（即不在说话的地方）。注意：这两个句式后接副词时，需省to。E.g. He has gone there.

    五、 忘记把already变成yet

    例：I have already finished my homework.(变一般疑问句)

        Have you already finished your homework?

    答案： Have you finished your homework yet?

    解析：现在完成时态中，肯定句中有already，变否定句或疑问句时通常要改为yet．

    六、在条件、时间状语从句中用一般现在时表示将来

　　例：I'll go with you when I finish(finish) my homework.

    答案：have finished

    解析：在条件、时间状语从句中表示将来完成的动作，用现在完成时。但注意，此时表示这动作将在另一动作之前完成，若两动作同时发生，或几乎同时发生，则一般不用现在完成时。

    另外，现在完成时易与一般过去时弄混，前边已经讲过,这里不在重复

 

专项练习：

一、单选

1 You have _____ a tall young man.

 A grown  B grown  into  C grown us  D grown up

2 He has ____ the watch for a year.

 A buy  B bought  C have  D had

3 Has your brother _____ the dog?

 A kept in  B fed  C fed on  D kept on

4I _____this book for two weeks, I have to return it now.

A borrowed  B have  borrowed   C kept  D have kept

5 Have you ever _____to the Great Wall? It's very beautiful.

 A gone  B been  C went  D go

6 Her brother _____the Party since 1978.

  A joined  B has joined  C has been in  D was in

7 The Greens _____many places of interest since they came to China.

 A will visit  B visited  C have visited  D visit

8 I'm sorry, I ____ your name.

 A had forgotten  B forgot  C have forgotten  D forgotten

9 The bookshop _____ for eight years.

 A has been open   B has been opened   Chas opened   D has open

10 We have       all the paper so we need to buy some.

 A used up  B made of   C filled with  D hunted for

11 The flower I ____grown up.

 A planted has   B planted have   C has planted   D have planted

 二、填空

1 Have you ever ______(take) a train?

2 It _________(be ) more than three years since Jim ______(leave) here.

3 Have you _____(make)friends with your new classmates yet?

4 I _______(have) my lunch and I'm not hungry now.

5 Jim has never seen a panda, _____he?

6 We ______(be) good friends since we met at school.

7 We can't find him anywhere. Perhaps he______(go) home.

8 He _____(read) the book before.

9 Mr. Green _____(teach) us a lot about social studies since September.

10 I _____never____ (meet) her sister before.

 

答案：１B  2 D  3 B  4D  5 B  6 C  7 C   8 C  9 A   10 A   11 A

1 taken   2 has been, left   3made   4 have had   5 has