1、八年级英语下册Unit 8现在完成时知识讲解和练习一、基本认识1.意义表示过去发生的动作，对现在造成的影响或结果。表示在过去已经开始，并持续到现在的动作或状态。如：Ive already had my lunch.【表示我已经吃过午餐，并且现在不饿】Ive lived here for 10 years.= Ive lived here since 10 years ago.【表示我10年前就住在这里，并且现在也住这里】2.基本构成have/has +过去分词have:第一人称，第二人称及第三人称复数has:第三人称单数肯定句：主语+have/has+过去分词否定句：主语+havent（hav
2、e not）+过去分词主语+hasnt（has not）过去分词疑问句：Have /Has +主语+过去分词.?如：I have finished my homework.I havent finished my homework.Have you finished your homework?3.标志词标志词比较多，如already,ever,never,since,for,just,yet,recently,once，over，in the past+一段时间等等。总结如下：如：She has already lived here for 5 years.Have you ever bee
3、n to Paris?I have never read the book The Journey To The West.My father has worked here since 2008.Ive just heard the bad news.Its too early.The supermarket hasnt been opened yet.I have to keep a diary because I have gained weight recently.I have been to Shanghai twice.Ive learnt a lot new math know
4、ledge during my stay at my aunts.A lot of changes have taken place in China in the past 40 years.二、高频易错1.since和for的区别for+时间段since+时间点since+一段时间+ago=for +时间段since +从句（一般过去时）Its+一段时间+since（一般过去时句子）如：I have worked here for 12 years.I have lived here since 2008.The film has been on since 10 minutes ago.
5、Two hours have passed since he arrived here.Its three years since my grandpa died.2.have been to/have gone to/have been inhave been to 去过，已经回来have gone to 去了，还没回来have been in 一直都在如：I have been to Beijing twice.I have never been to Paris.Where has Tom gone to?Sophie is not here.She has gone to Shangh
6、ai.My family have been in Chongqing for 80 years.三、重难点内容1.瞬间动词与延续性动词瞬间动词也称为【终止性动词】和【非延续性动词】。顾名思义，这类动词所表示的动作在瞬间就可以完成，没有延续下去，动作开始到结束的时间很短。通常瞬间动词表示的是一次性动作或者动作的相应结果。不能和since/for连用。延续性动词又称为【持续性动词】，这类动词表示可以持续的动作，或者状态。动作可以延续一段时间，所以这些动词就可以和since与for连用。如：I have borrowed this book for 7 days. I have kept this
7、 book for 7 days.My grandpa has died since 10 years ago. My grandpa has been dead since 10 years ago.The restaurant has closed since 10 minutes ago. The restaurant has been closed since 10 minutes ago.2.瞬间动词和延续性动词转换看看例句：She has arrived here since three hours ago.（她三个小时前就已到这里了。）这句话大家觉得是正确的还是错误的？错误的【a
8、rrive】是瞬间动词，能用于现在完成时，但不能与since/for连用。更改【1】arrivebeShe has been here since three hours ago.【2】一般过去时She arrived here three hours ago.注意内容：现在完成时肯定句中，瞬间动词作谓语时，不能和since/for表示一段时间的状语连用。记住瞬间动词可以用于现在完成时，只能不能和since/for连用。瞬间动词可以替换为延续性动词，替换为延续性动词后，可以和since/for连用。看下面这句话：“他已经去世三年了。”去世，对应的动词，【die】。对照上表，die是瞬间动词，转
9、换为延续性动词是be dead。如果要使用谓语动词【die】，那么就要用一般过去时;如果要和since/for连用，【die】就要替换为【be dead】。所以这句话对应的表达有5种：（1） He died three years ago.【一般过去时，标志词three years ago】（2） He has been dead for three years.【现在完成时，标志词for+一段时间】（3） He has been dead since three years ago.【现在完成时，标志词since+一段时间】（4） It is three years since he die
10、d.【It is +一段时间+一般过去时从句】（5） Three years have passed since he died.【一段时间+have/has passed+since+一般过去时从句】四、练习题1.单项选择( ) 1.-Where _ the recorder? I cant see it anywhere.- I _ it right here.But now its gone!A.did you put; have put B.have you put;putC.had you put; was putting D.were you putting; have put(
11、) 2.My father _ here since he _ to this school.A.taught; came B.has taught; cameC.taught; has come D.has taught; has come( ) 3.I am sorry youve missed the train.It_ 10 minutes ago.A.left B.has left C.has been left D.had left( ) 4.Hi! Jim! Nice to meet you again! Its one year since I last _ you.A.saw
12、 B.see C.seeing D.have seen( ) 5.- Have you visited the Dinosaur World,Elsa? （宁波）- Yes, I _ it yesterday.A.have visited B.had visited C.visited D.visit( ) 6.- Nice to see you.I _ you for along time.- I _ in Bejing.Ive just come back.A.hadnt seen; am B.havent seen; was C.didnt see; will be D.havent s
13、een; shall be( ) 7.-What is the weather like this summer here?- There _ very little rain.A.has B.has been C.are D.have been( ) 8.When _you _ your dictionary?A.did; lose B.has; lost C.will; lose D.does; lose( ) 9.Where _ you _? Which answer is not right?A.are; going B.have; been C.did; go D.are; doin
14、g( ) 10.There _ many great changes in my hometown since ten years ago.A.were B.have C.are D.have been 【参考答案】15 BBAAC 610 BBADD2.单项选择1.Li Hong has _ the army for 2 years.A.joined B.be in C.been in D.joined in2.We have been friends since _.A.children B.five years C.five years ago D.five years before3.
15、Mike _ the story for a month.A.has bought B.has had C.had had D.has borrowed4.You _ that question three times.A.already askedB.have already askedC.already have asked D.asked already5.Those foreign friends left Guangzhou _.A.since last week B.a week ago C.for a week D.since a week ago6.I _ at this sc
16、hool for two years.A.am studying B.study C.studied D.have studied7.They _ in the city since last summer.A.live B.didnt live C.have lived D.live8.Mrs.Wang has lived in Haikou _ 1992.A.since B.from C.after D.in9.Mr.Black _Chinasince the summer of 1998.A.has been to B.has been in C.has come to D.came t
17、o10.His father _ for years.A.has died B.has been dead C.died D.dies【参考答案】1-5 CCBBB6-10 DCABB3.用 already或 yet填空。1.-Have they taken down the old pictures _? -No, not _.2.Most of us have finished our compositions _3.He said he hadnt visited the exhibition _.【参考答案】yet;yet/ already/ yet4.用 since或 for填空。1
18、.We have learned five lessons _ the beginning of this term.2.Mrs.Liao has been in hospital _last week.3. I have stayed at my aunts _two weeks.【参考答案】since/ since/ for5.用have/has been to/in, have gone to及go的各种形式填空。1. Where is Jack? He _ his country. 2.John _Englandsince he came back.3.How long _ you _
19、this village? 4.The Smiths _ Beijing for years.5. _you ever _ America? Yes, I _ there many times.6. I _this school since three years ago.7. When _ he _? He _ an hour ago.8. Would you like to _ the zoo with me? Yes, but I _there before.9. Where _ you _ just now? I _ the zoo.10.He often_ swimming. 11._ you _ there last year?12._ they often _skating in winter? 【参考答案】1.has gone to 2.has been in 3.have; been in 4.have been in 5.Have; been to; have been6.have been in 7.did; go; went 8.go; have been 9.did; go; went to 10.goes 11.Did; go 12.Do; go 6
