八年级英语Pastampnbspandampnbsppresent教案

　　unit 1 past and present
　　一. 教学内容：
　　unit 1 past and present grammar
　　二. 教学目标：
　　掌握unit1的语法: present perfect tense 现在完成时的用法
　　（一）基本概念
　　1、定义
　　现在完成时用来表示之前已发生或完成的动作或状态，但它的影响现在还存在；也可表示持续到现在的动作或状态。
　　2、构成： have (has) +过去分词。规则变化的过去分词与过去式的变化一样，在动词词尾加ed; 不规则变化的过去分词见不规则动词表，需要同学们记忆。
　　3、句型：
　　现以see the film为例将现在完成时的肯定句，否定句和疑问句列表如下：
　　肯定句：i/you/we/they have seen the film. he/she /it has seen the film.
　　否定句：i/you/we/they have not/ haven’t seen the film.
　　he/ she/it has not/hasn’t seen the film.
　　疑问句：have i/you/they seen the film? yes, you/ we/i/they have. no, you/ we/i/they haven’t.
　　has he/she/it seen the film? yes, he/ she/ it has. no, he/ she/ it hasn’t.
　　（二）用法：现在完成时既涉及过去，又联系现在。
　　用法一：表示过去发生或已经完成的某一动作对现在造成的影响或结果。常与just（刚刚），already（已经），never（从来没有），ever（曾经），before（以前），yet（仍然），once（一次），twice（两次），many times（很多次），how many times（多少次），so far（迄今为止），during the past（last）three years（最近三年来）等连用。
　　※ 副词的位置：①just常用于肯定句中，放在have / has后，he has just come .
　　②never表示否定, 放在have / has后, he has never visited the great wall.
　　③ever用于疑问句中,句型为: have / has 主语 ever  过去分词？＂……曾经……过吗？＂用于询问某人过去的经历。have you ever been to the farm？
　　④before用于句末，the woman has never heard of that before.
　　⑤yet 用于句末或not 之后. has the train arrived yet? no, not yet.
　　⑥already用于肯定句, have / has 之后或句末.we have already finished it.
　　⑦so far用于句首或句末. so far, we have visited the moon.
　　用法二：表示过去已经开始，一直延续到现在的动作或状态。时间状语有：
　　（三）现在完成时态中可以和表示一段时间的状语（for，since，how long, all one’s life）连用的动词必须是表示延续的情况或动作的动词，即延续性动词。如：be，have，know，live，work，study，learn，teach，keep，speak，talk，draw，wait，wear，walk，sleep，drive，write，do，clean等。
　　i have been a teacher for nearly 20 years. how long has he lived here?
　　（四）延续性动词的现在完成时可和包括＂现在＂在内的（到说话时仍未结束）表示一段时间的状语连用。如this morning，today，this week，these days
　　he has been to beijing three times this year.
　　he has written two letters this morning.（说话时间在上午）
　　he wrote two letters this morning.（说话时间在下午或晚上）
　　（五）英语中还有一些动词的意义决定它们所表示的动作不能延续，只是一瞬间
　　就结束的动作,这类动词叫做＂非延续性动词＂，常见的有：come，go，arrive，reach，see，hear，close，open，leave，begin，start，lose，buy，fall，join，die，get up，become，borrow，lend，find，finish，receive等。这些动词可用于现在完成时，说明某个动作的结果还存在，但不能和表示一段时间的状语（how long，for，since）连用。
　　he has come back.（ ）
　　he has come back for two hours.（ ）
　　※ 但在否定句中，非延续性动词也可用表示一段时间的状语来修饰，如
　　i haven’t heard from my father for a long time.
　　we haven’t seen him since 1999.
　　（六）当终止性动词（非延续性动词）与表示一段时间的状语（how long，since，for，all one’s life）相矛盾时,改正错句的方法有如下几种:
　　（1）用副词ago把现在完成时的句子改为一般过去时.
　　he has come back for two weeks.（错）
　　改为: he came back two weeks ago.（正）
　　i have lost my bike for ten days. （错）
　　改为: i lost my bike ten days ago. （正）
　　（2）用＂it is / has been 时间 since 一般过去时态＂句型来改写。
　　he has joined the league for 3 years. （错）
　　it is 3 years since he joined the league.（正）
　　i have bought the book for 5 days. （错）
　　it is 5 days since i bought the book. （正）
　　he has died for 20 years. （错）
　　it is 20 years since he died. （正）
　　（3）用＂时间 has passed since 一般过去时态＂句型来改写。
　　he has left home for 20 years.
　　改为: twenty years has passed since he left home.
　　he has lost his pen for 2 days.
　　改为: two days has passed since he lost his pen.
　　（4）用系表结构来改写.
　　he has died for 20 years.
　　改为: he has been dead for 20 years.
　　the factory has opened since 1999.
　　改为: the factory has been open since 1999.
　　how long has he left?
　　改为: how long has he been away?
　　（5）用相应的延续性动词替代非延续性动词。
　　he has bought the book for two weeks.
　　改为: he has had the book for two weeks.
　　常见的相应转换形式如下:
　　borrow / lend keep, buy have, finish / end be over, arrive /come / go / move / reach /get to be in /at / be here /be there, begin / start be on , open be open , close be closed, die be dead , leave be away（from）, go to school be in school / be a student, get up be up, fall asleep be asleep , fall ill be ill, get to know know, lose be lost, become be, return / come back / get back be back, join be in / be a…member, join the army be in the army /be a soldier, receive / get a letter have a letter , catch / get a cold have a cold, begin to study study
　　他参军已有三年。
　　he has joined the army for three years.（错）
　　改为：
　　he has been in the army for three years / since three years ago.
　　he has been a soldier for three years / since three years ago.
　　he joined the army three years ago.
　　it is three years since he joined the army.
　　three years has passed since he joined the army.
　　（1）he came to our village two years ago.=he our village since two years ago.
　　（2）he left home three days ago. =he home for 3 days.
　　（3）i bought the watch 2 weeks ago. =i the watch since 2 weeks ago.
　　（4）it is 5 days since i borrowed the book. =i the book for 5 days.
　　（5）the film has begun. = the film for half an hour.
　　（6）i got to know him 10 years ago. =i him for 10 years.
　　（7）there is a factory. =there a factory for 20 years.
　　（8）our school opened in 1960. =our school since 1960.
　　（七）现在完成时中应注意的几个问题
　　1. have been to 和have gone to的区别
　　have been to 强调＂去过＂，现已不在那里，如：
　　he has been to the usa three times.
　　他到美国去过三次。（过去＂到美国＂，现在已＂不在美国＂）
　　have gone to主要强调的是＂去了＂，现在人不在说话的现场，如：
　　—where’s your mother? —你妈妈在哪？
　　—she has gone to the hospital. —她去医院了。
　　2. have been to 和have been in的区别
　　have been to强调人＂已回到原地＂，后面可接表示＂次数＂的状语。
　　eg. ① she has been to shanghai only once.
　　②—how many times has he been there? —he’s been there many times.
　　have been in表示某人＂已在某地停留一段时间，现仍在那里＂，其后常带表示一段时间的状语。
　　eg. ①they have been at the bus stop for half an hour.他们在车站呆了半小时。（现在仍然在车站）
　　②we have been in xi’an for two weeks.
　　我们在西安呆了两个多星期。（现仍在西安）
　　③how long have they been in china?
　　他们在中国呆了多长时间了？（仍在中国）
　　（八）如何通过与一般过去时做比较,进一步掌握现在完成时?
　　一般过去时和现在完成时的动作都发生在过去,但意义却不同.
　　如: i learned ten english songs（说明过去学过,现在是否记得,不是本句的内容）
　　i have learnt ten english songs.（learn发生在过去,但强调我现在懂英语歌曲）
　　i cleaned the blackboard half an hour ago.（只说明＂擦＂和其发生的时间）
　　i have cleaned the blackboard.（说明现在黑板是干净的）
　　the teacher has written some new words on the blackboard（黑板上现在有单词）
　　the teacher wrote some new words on the blackboard（黑板上现在没有单词）
　　（2）一般过去时可以和表示过去的时间状语连用,如:yesterday, last year, three days ago, just now, 等。现在完成时不能和表示过去的时间状语连用,其时间状语可以是since…, for…, just, ever, never, before, already, yet , so far, all one’s life等
　　（九）规则动词的过去分词和它的过去式相同，即在原形后加－ed（－d）。已学近80个不规则动词的过去分词约有半数也和它的过去式相同，现分类如下，以利于同学们记忆：
　　1）原形中的元音字母有变化：
　　get-got-got, sit –sat-sat win-won-won spit- spat- spat shine –shone- shone
　　find- found- found hold-held-held meet- met-met stand- stood-stood
　　understand-understood-understood feed- fed-fed hang-hung-hung
　　2）原形中的辅音字母有变化：
　　make-made-made spill-spilt-spilt have/ has-had-had build-built-built
　　send-sent-sent lend- lent- lent spend-spent-spent
　　3）在原形后加t或d：
　　spoil-spoilt-spoilt learn-learnt-learnt mean-meant-meant hear-heard-heard
　　pay-paid-paid say-said-said lose-lost-lost lay-laid-laid
　　4）原形中的元音字母和辅音字母都有变化：
　　feel-felt-felt smell-smelt-smelt spell-spelt –spelt keep-kept-kept
　　sleep-slept-slept sweep-swept-swept leave-left-left sell-sold-sold
　　tell-told-told catch-caught-caught teach-taught-taught buy-bought-bought
　　bring-brought-brought think-thought-thought wear-wore-worn
　　5）与原形相同：
　　hit-hit-hit hurt-hurt-hurt let-let-let put-put-put read-read-read
　　set-set-set shut-shut shut cost-cost-cost cut-cut-cut
　　还有些不规则动词的过去分词与过去式不相同,为便于记忆,也分类如下:
　　1）原形中的元音字母有变化：
　　ring-rang-rung sing-sang-sung drink-drank-drunk swim-swam-swum
　　begin-began-begun sink-sank-sunk
　　2）在原形上加－en：
　　eat-ate-eaten fall-fell-fallen ride-rode-ridden write-wrote- written
　　be-was/were-been rise-rose-risen forget-forgot-forgotten
　　3：在原形上加－n：
　　see-saw-seen give-gave-given drive-drove-driven take-took-taken
　　mistake-mistook-mistaken draw-drew-drawn blow-blew-blown
　　grow-grew-grown know-knew-known show-showed-shown throw-threw-thrown
　　4）在过去式上加－n：
　　steal-stole-stolen break-broke–broken choose-chose-chosen speak-spoke-spoken wake-woke-woken
　　5）与原形相同：come-came-come run-ran-run become-became-become
　　6）原形、过去式和过去分词都不相同的：
　　do-did-done go-went-gone fly-flew-flown lie-lay-lain
　　7）个别动词有两个过去式和过去分词，一个为规则变化，另一个为不规则变化：
　　【典型例题】
　　1. i have already ______ the magazine for 2 weeks. i must return it to the library today.
　　a. lent b. bought c. borrowed d. kept
　　解析：答案选d。
　　这是一句现在完成时的句子，表示从过去开始持续到现在的行为，for 表示一段时间，后接时间长度，本句的意思应为：这本杂志我已经借了两个星期了。在这样的时间状语为＂for+时间长度＂的句子里，谓语动词要有可持续性，而不能为短暂性动词，因此，本题只能选d。因为＂lent＂，＂bought＂，＂borrowed＂均为短暂性动词，且＂bought＂，＂lent＂与句义不符。故选d。
　　下面列出一些短暂性动词的持续性表达：
　　arrive—be in borrow—keep buy—have fall ill—be ill
　　join—be in leave—be away from begin—be on die—be dead等等
　　2. —where are the children? — they ________ to beijing.
　　a. have been b. have gone c. have left d. have arrived
　　解析：答案选b。
　　本题首先可排除c，d选项。＂离开此地去北京＂为＂leave for beijing＂，＂到达北京＂为＂arrive in beijing＂. 然后再看a，b 选项，＂have been to＂意思是＂去过某地＂，表示曾经去过某地，现在已经回来或到其他地方，目前人已不在那里。＂have gone to＂意思是＂去了某地＂，表示人正去那里或已在去那里的途中。本题中，孩子们不在说话人所在的地方，所以应该选择b，表示他们已经去了北京或在去北京的途中。故选b。
　　3. — _______ has he taught english in this school? —for 2 years.
　　a. how long b. when c. how soon d. how often
　　解析：答案选a。
　　＂how long＂问的是＂一段时间＂，这句话的意思是，他在这所学校教英语多久了，回答为＂两年了。＂＂how long＂可与现在完成时一起用。＂when＂问的是一个时间点，可以和将来时、过去时连用，有时也可以和进行时放在一起用，但＂when＂不能和完成时一起使用。＂how soon＂意思是＂多久以后＂，用在将来时前面，而＂how often＂问的是一个频率，可解释为＂多久一次＂，回答多为＂once a week.＂＂twice a month＂等等。故选a。
　　4. —do you still write to your friends these days?
　　no. but i used ______ that when i was at school.
　　a. do b. did c. to doing d. to do
　　解析：答案选d。
　　本题涉及到＂used＂的几个不同用法，＂be used to doing sth.＂表示＂习惯于做某事＂，＂used to do sth.＂表示＂过去常常做某事＂，而＂be used to do sth.＂则表示＂被用来做某事＂，主语多为＂sth.＂.本题＂used＂前面没有be动词，再加上说的是过去我在学校里的事情，所以采用＂used to do sth.＂这个词组，整句话的意思就是，当我在学校里的时候，我常常那么做。故选d。
　　5. she was very _____________ at the _________ news.
　　a. surprised; surprising b. surprised; surprised
　　c. surprising; surprised d. surprising; surprising
　　解析：答案选ａ。
　　＂be surprised at sth.＂表示＂对……感到惊奇＂，主语是＂somebody＂，
　　＂surprising＂表示＂令人惊奇的＂，主语多为 ＂something＂, 句子的意思是，她对＂这个令人惊奇的消息感到很惊奇＂。与此相类似的词语还有一些，如＂exciting令人激动的＂，＂excited感到激动＂，又如＂interesting 有趣的＂，＂interested 感兴趣的＂等等。故选a。
　　6. he has never _______ a pen before.
　　a. lose b. to lose c. lost d. losing
　　解析：答案为c。 本题主要考查现在完成时态对谓语动词的要求。现在完成时态谓语动词的结构是have (has)+ 过去分词。本题空白处需要填过去分词，这样的话，那a、b、d就都不对了。
　　7. 误：the twins have not got home already.
　　正：the twins have not got home yet.
　　解析：本题主要考查yet 与 already的用法区别，两个词都是副词，常与完成时态连用。yet 用于否定句和疑问句，通常置于句尾；already 常用于肯定句，当用于疑问句时，表示惊讶或希望得到肯定的答复，不用于否定句中，它可以在主要动词之前，也可置于句末。
　　8. tim has been at the factory_________ two years ago.
　　a. for b. since c. before d. after
　　解析：答案为b。 本题主要考查时间状语与谓语的关系。for后跟时间段表示一段时间，since 后跟时间的起点，表示一段时间，before 表示在什么时间之前，after则表示在什么时间之后。本句是完成时态，指自两年前以来如何，且两年前是个时间的（起）点，因此，此处应用since.
　　9. 误：i saw the film twice already.
　　正：i’ve seen the film twice already.
　　解析：本题主要是一般过去时态与现在完成时态的概念错误。这电影我已看过两遍，说明我现在对电影内容很了解，故要用现在完成时态。
　　10. —______you _____ your watch?
　　— no, ______.
　　a. did, find out, i didn’t b. have, found, not yet
　　c. have, looked for, i haven’t d. did, find, not yet
　　答案：选＂b＂。全句应用现在完成时，强调到现在为止的情况＂是否找到了手表＂，答语：not yet 相当于说 i haven’t found it yet.
　　11. i have never seen the film ______.
　　a. ago b. just now c. before d. later
　　答案：选＂c＂。动词时态为现在完成时，与之搭配的词必须是ever, never, already, yet, before, recently 等词。而 ago, just now 等只能用于一般过去时的句子中，用later意思不通。
　　12. aunt li _________ her home town for a long time.
　　a. has left b. left c. has gone to d. has been away from
　　答案：选＂d＂。与 for a long time搭配的动词应该表示延续性，go, leave是短暂动词，故不能选。