11.10 比较过去时与现在完成时
　　
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　　　 1）过去时表示过去某时发生的动作或单纯叙述过去的事情，强调动作；现在完成时为过去发生的，强调过去的事情对现在的影响，强调的是影响。
　　　
　　　 2）过去时常与具体的时间状语连用，而现在完成时通常与模糊的时间状语连用，或无时间状语。
　　一般过去时的时间状语:
　　yesterday, last week，...ago, in1980, in October, just now, 具体的时间状语
　　共同的时间状语:　
　　this morning, tonight,this April, now, once，before, already, recently，lately　
　　现在完成时的时间状语
　　for, since, so far, ever, never, just, yet,　　　　　　till / until, up to now, in past years, always,
　　不确定的时间状语
　　　
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　 3）现在完成时可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.
　　　 过去时常用的非持续性动词有come, go, leave, start, die, finish, become, get married等。
　　　举例：
　　　 I saw this film yesterday.
　　　　（强调看的动作发生过了。）
　　　 I have seen this film.
　　　　（强调对现在的影响，电影的内容已经知道了。）　
　　　 Why did you get up so early?
　　　　（强调起床的动作已发生过了。）
　　　 Who hasn't handed in his paper?　
　　　　（强调有卷子，可能为不公平竞争。）
　　　 She has returned from Paris.　
　　　　 她已从巴黎回来了。
　　　 She returned yesterday.
　　　　 她是昨天回来了。
　　　 He has been in the League for three years.
　　　　(在团内的状态可延续)
　　　 He has been a League member for three years.
　　　　(是团员的状态可持续)
　　　 He joined the League three years ago.　
　　　　( 三年前入团，joined为短暂行为。)
　　　 I have finished my homework now.　
　　　
　　　 ---Will somebody go and get Dr. White?
　　　 ---He's already been sent for.　
　　　 句子中如有过去时的时间副词（如 yesterday, last, week, in 1960）时，不能使用现在完成时，要用过去时。
　　　 （错）Tom has written a letter to his parents last night.
　　　 （对）Tom wrote a letter to his parents last night.
　　11.11 用于现在完成时的句型
　　
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　　1）It is the first / second time.... that...结构中的从句部分，用现在完成时。
　　　 It is the first time that I have visited the city.
　　　 It was the third time that the boy had been late.
　　2）This is the... that...结构，that 从句要用现在完成时.
　　　 This is the best film that I've (ever) seen.
　　　　　 这是我看过的最好的电影。
　　　 This is the first time (that) I've heard him sing.　这是我第一次听他唱歌。
　　典型例题
　　(1) ---Do you know our town at all?　
　　　 ---No, this is the first time I ___ here.
　　A. was　 B. have been　 C. came　 D. am coming
　　　 答案B. This is the first time 后面所加从句应为现在完成时，故选B。
　　(2) ---Have you ____ been to our town before?
　　　 ---No, it's the first time I ___ here.
　　A. even, come　 B. even, have come　　C. ever, come　 D. ever, have come
　　　 答案D. ever意为曾经或无论何时，反意词为never，此两词常用于完成时。 This is the largest fish I have ever seen. It is / was the first time +that-clause 的句型中，从句要用完成时。
　　　 注意：非延续性动词的否定形式可以与表示延续时间的状语连用。即动作不发生的状态是可以持续的。
　　（错）I have received his letter for a month.
　　（对）I haven't received his letter for almost a month.
　　小升初英语语法复习－动词时态2
　　发表时间：2009-1-22 17:13:25 点击次数：24096次 来源：转载
　　　
　　11.12 比较since和for
　　
　　　　Since 用来说明动作起始时间，for用来说明动作延续时间长度。
　　　　I have lived here for more than twenty years.
　　　　I have lived here since I was born..
　　　　My aunt has worked in a clinic since 1949.　
　　　　Some new oilfields have been opened up since 1976.
　　　　I have known Xiao Li since she was a little girl.　
　　　　My brother has been in the Youth League for two years.　
　　　　I have not heard from my uncle for a long time.
　　　　注意：并非有for 作为时间状语的句子都用现在完成时。
　　　　 I worked here for more than twenty years.
　　　　　(我现在已不在这里工作。)
　　　　 I have worked here for many years.　　　
　　　　　(现在我仍在这里工作。)
　　　　小窍门：　当现在完成时+一段时间，这一结构中，我们用下面的公式转化，很容易就能排除非延续动词在完成时中的误使。
　　　　1)　(对) Tom has studied Russian for three years.
　　　　　 = Tom began to study Russian three years ago, and is still studying it now.
　　　　2)　(错) Harry has got married for six years.
　　　　　 = Harry began to get married six years ago, and is still getting married now.
　　　　显然，第二句不对，它应改为 Harry got married six years ago.　或 Harry has been married for six years.
　　11.13 since的四种用法
　　
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　　　 1) since +过去一个时间点　(如具体的年、月、日期、钟点、1980, last month, half past six)。
　　　 I have been here since 1989.
　　　
　　　 2) since +一段时间+ ago
　　　 I have been here since five months ago.
　　　 3) since +从句　
　　　 Great changes have taken place since you left.
　　　 Considerable time has elapsed since we have been here.
　　　 4) It is +一段时间+ since从句
　　　 It is two years since I became a postgraduate student.
　　11.14 延续动词与瞬间动词
　　
　　1) 用于完成时的区别
　　　　延续动词表示经验、经历； 瞬间动词表示行为的结 果，不能与表示段的时间状语连用。
　　　　 He has completed the work.　　他已完成了那项工作。 (表结果)
　　　　 I've known him since then.　　 我从那时起就认识他了。(表经历)
　　2)　用于till / until从句的差异
　　　　 延续动词用于肯定句，表示"做......直到......" 瞬间动词用于否定句，表示"到......，才......"
　　　　 He didn't come back until ten o'clock.
　　　　　　他到10 点才回来。
　　　　 He slept until ten o'clock.　　　　　
　　　　　　他一直睡到10点。
　　　
　　典型例题
　　1. You don't need to describe her. I ___ her several times.　
　　A. had met　B. have met　 C. met　D. meet
　　　 答案B. 首先本题后句强调对现在的影响，我知道她的模样，你不用描述。再次，several times告知为反复发生的动作，因此用现在完成时。
　　2.---I'm sorry to keep you waiting.
　　　---Oh, not at all. I ___ here only a few minutes.
　　A. have been　 B. had been　 C. was　D. will be
　　　 答案A. 等待的动作由过去开始，持续到现在，应用现在完成时。
　　11.15 过去完成时
　　
　　1） 概念：表示过去的过去
　　----|-------|-----|---->其构成是had +过去分词构成。
　　那时以前　 那时　现在　　　　　　
　　2） 用法
　　　a.　在told, said, knew, heard, thought等动词后的宾语从句。
　　　　 She said (that) she had never been to Paris.
　　　b. 状语从句
　　　　 在过去不同时间发生的两个动作中，发生在先，用过去完成时；发生在后，用一般过去时。
　　　　 When the police arrived, the thieves had run away.
　　　c. 表示意向的动词，如hope, wish, expect, think, intend, mean, suppose等，用过去完成时表示"原本...，未能..."
　　　　 We had hoped that you would come, but you didn't.
　　3)　过去完成时的时间状语before, by, until , when, after, once, as soon as。
　　　 He said that he had learned some English before.
　　　 By the time he was twelve, Edison had began to make a living by himself.
　　　Tom was disappointed that most of the guests had left when he arrived at the party.
　　典型例题　
　　　 The students ___ busily when Miss Brown went to get a book she ___ in the office.　
　　A. had written, left　B，were writing, has left　 C. had written, had left　D. were writing, had left
　　　 答案D. "把书忘在办公室"发生在"去取书"这一过去的动作之前，因此"忘了书"这一动作发生在过去的过去，用过去完成时。句中when表示的是时间的一点，表示在"同学们正忙于......"这一背景下，when所引导的动作发生。因此
　　前一句应用过去进行时。
　　注意：　had no ... when　　　　　还没等...... 就......
　　　　　　had no sooner... than　　刚...... 就......
　　　 He had no sooner bought the car than he sold it.
　　11.16 用一般过去时代替完成时
　　
　　1)　两个动作如按顺序发生，又不强调先后，或用then，and，but 等连词时，多用一般过去时。
　　　　 When she saw the mouse，she screamed.
　　　　 My aunt gave me a hat and I lost it.
　　2 ) 两个动作相继发生，可用一般过去时；如第一个动作需要若干时间完成，用过去完成时。
　　　　 When I heard the news, I was very excited.
　　3)　叙述历史事实，可不用过去完成时，而只用一般过去时。
　　　　 Our teacher told us that Columbus discovered America in 1492.
　　11.17 将来完成时
　　
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　　　1) 构成will / be going to do sth.
　　　2) 概念　
　　　　a. 状态完成：表示某事继续到将来某一时为止一直有的状态。
　　　　b. 动作完成：表示将来某一时或另一个将来的动作之前，已经完成的动作或一获得的经验。
　　　　　They will have been married for 20 years by then.
　　　　　You will have reached Shanghai by this time tomorrow.
　　11.18 现在进行时
　　
　　　现在进行时的基本用法：
　　　a. 表示现在( 指说话人说话时) 正在发生的事情。
　　　　 We are waiting for you.
　　　b. 习惯进行：表示长期的或重复性的动作，说话时动作未必正在进行。
　　　　 Mr. Green is writing another novel.　
　　　　　(说话时并未在写，只处于写作的状态。)
　　　　 She is learning piano under Mr. Smith.
　　　c. 表示渐变的动词有：get, grow, become, turn, run, go, begin等。
　　　　 The leaves are turning red.