Unit 8 Have you read Treasure Island yet？现在完成时与一般过去时辨析（课件10张）

(共10张PPT)
一般过去时和现在完成时辨析
一、一般过去时与现在完成时的定义 区别
1、一般过去时表示在过去某个时间发生的动作或者存在的状态，也表示过去经常反复发生的动作强调动作发生在过去某一时间。与现在不发生联系，是过去的动作。
past
now
2、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，或者从过去发生一直持续到现在（包括现在）的某个动作或者状态。主要强调的是对现在的影响或者动作、状态持续到现在。
now
We didn’t see him last year.我们去年没有见过他。（强调去年没见过，现在不一定见没见。）
We haven’t seen him.我们没有见过他。
（现在仍然未见）
He lived here last night.
他昨天晚上住在这儿（只是昨晚住）
He has lived here since he was born .
自他出生以来一直住在这儿
（居住这个动作延续到 现在）
二、时间状语的区别
一般过去时
现在完成时
I was born in 1984.
I went to London last month.
They haven't finished their homework yet.
I have never been to the Great Wall.
He has been a soldier for three years.
I have lived here since my childhood.
yesterday /last week/…ago/ in1980/ in October/ just now
1、 so far/ ever/ never/ just/ yet/till/until/ up to now/ in past years/always等
2、 since+时间点或for+时间段
共同的时间状语:this morning, tonight, this April, now, once，before, recently，lately 等
例如：
I ate an hamburger this morning.
I have eaten an hamburger this morning.
三、需要注意的问题
1、动词的延续性 现在完成时当表示持续到现在的动作或状态，动词一般是延续性的，如live, teach, learn, work, study, know等.
而如果仅仅用现在完成时表示过去动作对现在的影响或者用一般过去时则可用非延续性动词。
例如：
He has been a soldier for three years.他参军三年了。
He has already joined the army.他已经参军了。
He joined the army last year. 他去年参军了。
2、一般过去时与现在完成时的句型转换
一般过去时的肯定句变否定句和一般疑问句时要添加助动词did。而现在完成时肯定句变一般疑问句或否定句时直接在助动词have 、has上变。
例如：
He left Beijing last year.
Did he leave Beijing last year (变一般疑问句）
He didn’t leave Beijing last year. （变否定句）
He has left Beijing.
Has he left Beijing (变一般疑问句）
He hasn’t left Beijing. （变否定句）
练一练
1、He ______a book yesterday. (read)
He _____already ______30 books. (read)
The train ____ just_____. （leave）
The train _____here just now.
3、He stayed here last year. (变否定句）
He has stayed here for 3 years.( 变一般疑问句）
read
has
read
has
left
left
He didn’t stay here last year.
Has he stayed here for 3years