Tales of the unexplainedUnit 1Unit 1Grammar and usage现在完成时态现在完成时态have /has + 过去分词过去分词Present perfect tenseThe structure of the Present Perfect Tense is: subjectaux. vmain v+I haveseenET.+You haveeatenmine._Shehasnotbeento Rome._Wehavenotplayedfootball.?HaveyoufinishedIt?HashedoneIt?通常使用现在完成时的几种情况：通常使用现在完成时的几种情况：1 表示发生在过去对现在表示发生在过去对现在仍有影响仍有影响的动的动作。作。We have already cleaned the classroom .The disappearance of Justin has made Kelly very unhappy. I have already read the book. The boy has come back.2. 表示一个表示一个刚刚完成刚刚完成的动作的动作They have just returned from France. 3 表示过去发生表示过去发生反复多次反复多次的动作。的动作。 The city is very familiar to me because I have visited it twice.You dont need to describe her, for I have met her several times.This month I have been to Beijing for 5 times.常与twice,three times等连用4 表示过去开始的动作或状态一直延续到表示过去开始的动作或状态一直延续到现在现在表示动作只能用于某些带有延续意义的动词。表示动作只能用于某些带有延续意义的动词。 She has taught here since ten years ago. Since 1949, Chinese people have lived a better life. We have been in this school for 3 months. We have learned English for 10 years. 瞬间动作要用否定式才能延续 I havent seen her for 3 years. I havent seen her since last year.since +时间点时间点 for +时间段时间段these days recently so far in the past few years lately by now延续性与非延续性动词：延续性与非延续性动词：判断正误判断正误：延续性动词常与延续性动词常与for, how long, since 等引导的表等引导的表示一段时间的状语或状语从句连用。示一段时间的状语或状语从句连用。一些非延续性动词如一些非延续性动词如come, go, leave, die, join, marry 等用于现在完成时，一般不可以与表示一等用于现在完成时，一般不可以与表示一段时间的时间状语连用，此时应改为意义相近的段时间的时间状语连用，此时应改为意义相近的延续性动词来表达。延续性动词来表达。 1 He has died for 3 years. 2 He has been dead for 3 years. 3 He died 3 years ago. 4 It has been 3 years since he died. 5 How long have you borrowed it? FTTTFkept注意：注意：非非延续延续性性动词动词的的否定形式可以否定形式可以与与表示延续时间表示延续时间的的状语连用状语连用。即。即动作动作不不发生发生的状态是的状态是可以可以持续的。持续的。判断正误：判断正误：（）I have received his letter for a month.（）（）I received this letter a month ago.（）I havent received his letter for almost a month.错错对对对对1. Ill give you the book as soon as I _ (finish) it.2. If you _ ( see) the film, you will like it. 3.Ill go to the party as soon as(or when )I _ (finish)my homework.have finished have seen5. 在时间或条件在时间或条件从句从句中表示在将中表示在将来某个时间前要完成某个动作来某个时间前要完成某个动作have finished1 We _ (study) English for about five years.2 They _ (live) in the south since their daughter was born.3 I _ (read) your article three times. Its well written.4 The student _ (finish) her homework already.5 The police _ (just finish) searching the area.have studiedhave livedhave readhas finishedhave just finished现在完成时的时间标志现在完成时的时间标志1不表示具体或确定时间的不表示具体或确定时间的 一些状语往往可一些状语往往可成为现在完成时的标志。成为现在完成时的标志。（1）already和和yet already一般用于肯定句中，yet一般用于否定句和疑问句中。 （2）ever和和never 多用于否定或疑问句中，表示“曾经”或“从未”等。Have you ever seen any aliens by yourself?I have never seen any aliens. (3) 表示到说话为止的过去时间状语表示到说话为止的过去时间状语，如just，before，up to now，the past few years等。He has been taken away by aliens before and he still has nightmares of that now. (4) 包括包括“现在现在”在内的时间状语在内的时间状语。如：now,today,this morning/month/year/term等。Have you met him this term?No,I havent.2.带有带有since或或for等表示等表示“一段时间一段时间”的的状语。状语。I havent seen my mother for two years and I miss her very much.关于现在完成时的几点补充关于现在完成时的几点补充：（1）现在完成时常与since连用，表示“自以来”,一直进行或者未进行某项活动，在since分句中，通常用非持续性动词的一般过去时，主句中的动词常用现在完成时，如果主句为表示时间长度的it be句型，动词可用一般现在时代替现在完成时。It is three months since he wrote to me.It is three months since he wrote to me.It is three months since he wrote to me.2)在在It/ That/ This is the first time +(that)从句中从句中,当主句谓语为当主句谓语为is/will be时时,that从句中的动词用现在完成时从句中的动词用现在完成时.It is the first time that Ive been here.当主句动词为当主句动词为was时时,that从句中的动词从句中的动词通常用过去完成时通常用过去完成时.It was the first time this year that he hadnt worked on Saturday.这是我第一次上网冲浪这是我第一次上网冲浪This is the first time that I have surfed the Internet. 1. -Do you know our town at all?-No, this is the first time I _ here. A. was B. have beenC. came D. am coming B2. -Have you _ been to our town before?-No, its the first time I _ here.A. even, came B. even, am comingC. ever, come D. ever, have come D3)先行词是先行词是最高级形式或被最高级形容最高级形式或被最高级形容词词修饰时修饰时,定语从句常用现在完成时定语从句常用现在完成时.This is the best film that Ive seen.现在完成时现在完成时与一般过去时的区别与一般过去时的区别：一般过去时一般过去时表示发生在过去的动作，和表示发生在过去的动作，和现现在在无关无关；现在完成时现在完成时则强调某一发生在过去的动作则强调某一发生在过去的动作与现在的关系，如对现在产生的与现在的关系，如对现在产生的结果或影结果或影响响等。等。He _ (work) in the city for ten years.workedhas workedI _(see) this film yesterday. （强调看的强调看的动作发）动作发）I _ (see) this film. （强调对现在的强调对现在的影响，电影的内容已经知道了）影响，电影的内容已经知道了）He _ (be) in the League for three years. （他仍然是一名团员他仍然是一名团员)He _ (join) the League three years ago. （强调加入的动作发生在过去）强调加入的动作发生在过去）sawhave seenhas been joined现在完成时与一般过去时常用的时间状语：现在完成时与一般过去时常用的时间状语：一般过去时常与一般过去时常与具体具体的时间状语连用，的时间状语连用，而现在完成时通常与而现在完成时通常与模糊模糊的时间状语连用，的时间状语连用，或或无无时间状语。时间状语。 一般过去时的时间状语：一般过去时的时间状语：yesterday, last week，ago, in1980, in October, in the past等，皆为具体的时间等，皆为具体的时间状语。状语。 现在完成时的时间状语：现在完成时的时间状语：for, since, already, yet, so far, up to now, ever, never, recently, lately, just, in the past years,等，皆为不确定的时间等，皆为不确定的时间状语。状语。一般过去时还是现在完成时？一般过去时还是现在完成时？1 They _ (move) to the south in 1990 and _ (live) there since then.2 Eric _ (leave) home last year and _ (just come) back.3 Justin _ (be) away from home for several days. He_ (disappear) last Friday.4 They _(buy) this house three years ago and they _ (live) here since then. movedhave livedlefthas just comehas beendisappearedboughthave lived My friend Jack has just sent me an e-mail, telling me about his travels around the world. He_(just be) to Qomolangma Base Camp and _(see) a Yeti there. He is still very excited about it. He _( visit) the great Pyramid in Egypt too. He says that he _(love) Egypt but he _( not visit) all the pyramids yet. He _( swim) in Loch Ness, but luckily he _( never meet) the Loch Ness Monster! He _(dive) in the India Ocean many times looking for treasure. Although he _ ( find) many sunken ships, he _( not find) any treasure. _he _(be ) to the Great Wall before? Im not sure-but I have. has just been saw has visited loves hasnt visited has swum has never met has dived has found hasnt found Has been