1、Unit 3 Computers,Two Tasks:The Present Perfect TenseThe Present Perfect Passive Voice,The Present Perfect Tense,现 在 完 成 时,I bought a new car two weeks ago .,I have bought a new car.,(两周以前购买，动作发生于过去。),(“我”“已经购买”，“已经拥有”，重在强调“有”的结果与影响。),I had my lunch at twelve oclock .,I have had my lunch .,(我在12 点吃的午
2、饭。),(我已经吃了午饭。),The Present Perfect Tense,含义I,1. 表示过去已经发生或已经完成的某一动作对 现在造成的影响或结果.,2. 不仅单纯表示一个过去的动作，而且还表示 该动作对现在的某种影响以及产生的后果； 既涉及过去，又联系现在。即现在完成时的 动作并非“现在”完成，而是“过去”完成，并 重在强调动作完成的结果与影响。,e.g. We have seen the new film .,构成：,The Present Perfect Tense,have/has + P.P.,Note: P.P.past participle 过去分词,e.g. Ive
3、seen this film.,He has lost his math book.,The Present Perfect Tense,过去分词的构成：, 一般动词，在词尾直接加“ -ed ”。, 以“ e ”结尾的动词，只在词尾加“ -d ”。, 以“辅音字母 + y ”结尾的动词，将 “y” 变为 “i” ， 再加“ -ed ”。, 重读闭音节结尾，末尾只有一个辅音字母， 先双写该辅音字母，再加“ -ed ”。,规则动词：规则动词的过去分词的构成规则与规则动词的过去式的构成规则相同。,work,visit,live,study,cry,play,stop,drop,不规则动词：不规则动词
4、的过去分词要特别牢记，详见课后附录中的不规则动词表。,The Present Perfect Tense,句式变化：,1)肯定句：,have/has + P.P.,2)否定句：,have/has + _ + P.P.,not,3)一般疑问句：,Have you done your homework?,I came here eight years ago .,I have lived here for eight years .,I have lived here since eight years ago .,我 8 年前来到这儿。,我在这儿住了已经 8 年了。,我自从 8 年前就住在这儿。
5、,表示过去已经开始，持续到现在的动作或状态，可以和表示从过去某一时刻延续到现在（包括“现在”在内）的一段时间的状语连用。,The Present Perfect Tense,含义II,连用的时间状语：,The Present Perfect Tense,for + 一段时间,since + 过去时间点 / 过去动作点（从句）,I have lived here for eight years.,I have lived here since eight years ago.,I have lived here since 1981.,The Present Perfect Passive Vo
6、ice,现 在 完 成 时 的 被 动 语 态,The Present Perfect Passive Voice,构成：,have / has + _ + done,been,主动变被动：,We have used every possible means to prevent the air pollution.,Every possible means _ to prevent the air pollution.,has been used,Exercises1. Both my brother work at the power station that _ in my hometo
7、wn. A. has set up B. has been set up C. was set up D. is set up2. -_ the sports meet will be put off. A. Ive been told B. Ive told C. Im told D. I told3. All the preparation for the task _, and were ready to start. A. completed B. complete C. had been completed D. have been done4. - How long _ at th
8、is job? - Since 1990. A. were you employed B. have you been employed C. had you been employed D. will you be employed,B,A,D,B,5. When and where to go for the on-salary holiday _ yet. A. are not decided B. have not been decided C. is not being decided D. has not been decided,B,6. No permission has _
9、for anybody to enter the building.（MET1988） A. been given B. given C. to give D. be giving,A,7. Until now, his homework has not _ finished. A. being B. be C. been D. to be,C,8. The windows _,you need not wash it again. A. is washed B. was washed C. has been washed D. will be washed,C,9. The snow on the street _, you can go home now. A. has been cleared B. had been cleared C. will be cleared D. was cleared,A,
