现在完成时精讲
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现在完成时 一、定义:动作或状态发生在过去,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。 二、构成： 肯定句：主语 + have/has + 动词过去分词 I/They have already finished reading the book. He/She has finished reading the book. 否定句：主语 + have/has not + 动词过去分词 I/They have not finished reading the book. He/She has not finished reading the book. 疑问句：have/has + 主语 + 动词过去分词 Have you finished reading the book? Has he finished reading the book? 三、用法： 1） 现在完成时所表示的动作在说话之前已完成，但对现在有影响，句中没有具体的时间状语。 此时多与never， ever， just，before，already，yet等连用。 I have already finished the TV play. already用于肯定句（“已经”），一般位于句中 ——Have you found your lost pen yet? yet用于疑问句（“到现在”）、否定句（“还”）句末 ——No, I haven’t found it yet. 2） 现在完成时所表示的动作开始于过去，持续到现在，也许还会继续持续下去。 常与for，since等一段时间状语连用。 We have lived here since 2000. since + 时间点 自从2000年我们一直住在这里。 =We began to live here in 2000, and is still living here now. I have learnt English for three years. for + 时间段 我学了3年英语了。 =I began to learn English three years ago, and am still learning English now. 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。) ※表示暂短动作的词（如come，go，borrow，lend，die，bur，marry等）的完成时不能与for，since等表示一段时间的状语连用。 例如：How long may I keep the book？这本书我可以借多久？Two weeks. 两周。 Borrow和lend 都是暂短性动词，当表示借多久时，用动词keep 四、比较过去时与现在完成时 1）强调的重点和意义不同：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。 I have just called her. I called her this morning. I have had my lunch. I had my lunch 5 minutes ago. 2）时间状语不同： 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 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, 3）动作的性质不同： 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。 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。） 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用。 (对) Tom has studied Russian for three years. = Tom began to study Russian three years ago, and is still studying it now. (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. 4)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. 五、用于现在完成时的固定句型 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。 六、 since的四种用法 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. 4) It is +一段时间+ since从句 It is two years since I became a postgraduate student. 七、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。 常见的短暂性动词转换成延续性动词 leave --- be away, borrow --- keep, buy --- have, begin/start --- be on, die --- be dead, finish --- be over, join --- be in+组织机构, be a member of+组织机构, open sth --- keep sth open, fall ill --- be ill, get up---be up, catch a cold --- have a cold, come here --- be here, go there --- be there, become --- be, come back --- be back, fall asleep --- be asleep, get to/ arrive/reach --- be (in), leave --- be away from, get to know --- know, go (get) out →be out， put on→ wear；catch a cold →have a cold等。 例:The old man died 4 years ago. ----The old man has been dead for 4 years. ---- It is 4 years since the old man died. ----Four years has passed since the old man died. He joined the Party 2 years ago. -----He has been in the Party for 2 years. I bought the book 5 days ago. ---- I have had the book for 5 days. 一、单项选择。 1、Both his parents look sad . Maybe they _________what's happened to him . A. knew B. have known C. must know D.will know 2、He has _______ been to Shanghai , has he ? A. already B.never C.ever D. still 3、Have you met Mr Li ______? A. just B. ago C.before D. a moment ago 4、The famous writer _____ one new book in the past two year . A. is writing B.was writing C.wrote D.has written 5、-Our country ______ a lot so far . -Yes . I hope it will be even ______ . A. has changed ; well B. changed ; good C. has changed ; better D. changed ; better 6、Zhao Lan ______already ______in this school for two years . A. was ; studying B. will ; study C. has ; studied D. are ; studying 7、We ______ Xiao Li since she was a little girl . A. know B. had known C. have known D. knew 8、Harry Potter is a very nice film .I_______ it twice . A. will see B. have seen C. saw D.see 9、-These farmers have been to the United States . -Really ? When _____ there ? A. will they go B. did they go C. do they go D. have they gone 10、-______ you ___ your homework yet ? -Yes . I _____ it a moment ago . A. Did ; do ; finished B. Have ; done ; finished C. Have ; done ; have finished D. will ; do ; finish 11、 His father ______ the Party since 1978 . A. joined B. has joined C. was in D. has been in 12、-Do you know him well ? - Sure .We _________ friends since ten years ago . A. were B. have been C. have become D. have made 13、-How long have you ____ here ? -About two months . A. been B. gone C. come D. arrived 14、Hurry up! The play __________ for ten minutes . A. has begun B. had begun C. has been on D. began 15、 It _____ ten years since he left the army . A. is B. has C. will D. was 16、 Miss Green isn't in the office . she_______ to the library . A.has gone B. went C.will go D. has been 过去完成时 过去完成时与现在完成时的比较 I have known him for three years.我认识他三年了。 I had known him when I was a student. 我当学生时，就已经认识他了。 过去完成时与现在完成时二者用法基本相同，但现在完成时以现在的时间为基点，过去完成时则以过去的时间为基点，与现在无关，即过去的过去。 I have finished my experiment. 我已经做完实验了。（表示现在说话时已经做完实验） By six o'clock，I had finished my experiment. 在六点以前，我就已经做完实验了。（表示在过去的某一时间six o'clock以前已经做完实验，与现在毫无关系） 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. 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. 本文来源：https://www.wddqw.com/doc/7cc49fecb9f67c1cfad6195f312b3169a451ea65.html