八年级下现在完成时全面知识点

1、现在完成时概念及用法:1表示过去发生或已经完成的动作对现在造成的影响或结果。常和just （刚刚），already（已经），yet （已经），never （从不），ever （曾经），before （以前），so far （到目前 为止）等时间状语连用。2表示从过去某一时刻开始一直持续到现在的动作或状态，还有可能继续下去，常和for或since引导的时间状语连用。此时的动词必须是延续性动词。构成：have/ has（助动词）+V过去分词肯定句：主语+ have/ has+V过去分词+其他否定句：主语 + have/ has+not+V过去分词+其他一般疑问句：have/ has+主语+ +V过

2、去分词+其他肯定回答：Yes,主语+ have/ has.否定回答：No,主语 + haven t/ hasn t.3常用标志词语already, never, ever, just, before, so far, yet , since + 过去的时间点 ,for + 一段时间等already常用于肯定句；yet用于否定句和疑问句。二常用句型结构辨析（一）have/has been to / have / has gone to / have/ has been in辨析： have/ has bee n to + 地名曾经去过某地”，现在已经回至U原地。He has been to En

3、gland twice.他曾经去过英国两次。（现在已经不在英国了 ）Have you ever been to the Great Wall?你到过长城吗？（现在已经不在长城上） have gone to + 地名 已经去某地了”， 说话时该人不在现场。He has gone to En gla nd。他已去英国了。（已经不在说话的地方，到达英国或者在去英国的路上） have bee n in + 地点待在某地，常与时间段搭配。I have bee n in Shan ghai for three years.（二）si nee 与 for 区别：1） for其后只能接表示“一段时间”的名词性

4、短语，可用于多种时态。表示动作或状态 持续的时间长短；since其后接表示“时间点”的短语或从句（一般过去时）；也可以接“一段时间+ago”, 常用于完成时态；还用于句型“ It 时间段+since+一般过去时态的句子”。表示过去某个时 间发生并持续至说话时的动作或状态。I ve lived in this citfor five years.He usually sleeps for 12 hours every day.we ve studied heresince 2009.She has worked here for five years.It s two yearince I ca

5、me to China.练习：用si nee和for填空1. Jim has bee n in Irela nd last Mon day.2. Jill has been in Ireland three days.3. His aunt has lived in Australia 15 days.4. Mike has been ill a long time. He has been in hospital October.2）for与since引导的时间状语可以进行相互替换My uncle has worked at this factory for five years.=My u

6、ncle has worked at this factory since five years ago.练习：I have studied En glish for five years- I have studiedEnglish.（三）延续性动词与非延续性动词延续性动词表示经过、经历；非延续性动词表示行为的结果，不能与表示一段时间的状语连用。I ve known him since then.表经历He has fini shed the work. 表结果（1 ）延续性动词与非延续性动词的用法: 非延续性动词与短暂性时间（点）连用非延续性动词也被称为终止性动词、瞬间动词，表示不能延续的

7、动作，这种动作发生后立即结束。如： ope n, die, close, beg in, fini sh, come, go, move, borrow, le nd, buy 等。非延续 性动词在肯定句中与表示时间点的状语连用，如two years ago.He joined the Army three years ago. 非延续性动词可用于It is/has been +时间段+si nee”句型It is/has been three years since I bought the book. 从我买这本书至U现在3 年了。I bega n to study En glish th

8、ree years ago.It is since I study Enlish.I moved to Chan gch un 5 years ago.Lily fin shed her homework 2 hours ago. 延续性动词表示能够延续的动作 ，如：learn, work, stand, know, walk, keep, wait, watch, read, sleep, live, stay等。延续性动词可以与表示时间段的状语for+段时间/since+时间点/sinee引导的从句(过去时)/since+段时间+ago等连用。(2)非延续性动词与延续性动词之间的转换:非延

9、续性动词转换为相应的延续性动词，用于现在完成时态，时间状语为for+段时间/since+时间点/sinee引导的从句（过去时）/since+段时间+agoThe old man died 4years ago.=The old man has bee n dead for 4 years.I borrowed the book 5 days ago.=I have kept the book since 5days ago.borrow -keep buy-have catch a cold -have a cold put on -wear get to know -know get to

10、sleep-sleep非延续性动词转化为be+ adj、adv、prep、n”beg in /start -be on go out-be out get to/arrive in/reach -be in die-be dead ope n-beope nleave- be away finish -be over fall ill -be ill get up- be up fall asleep-be asleepjoin -be a member of go to school - be in school become-be make friends -be friendscome/

11、go -be+相应的介词短语练习-同义句转换:1 I bought the dict ionary last year.1 havethe dictionary one year.2 The film bega n 5 minu tes ago.The filmfor 5 mi nu tes.3 His gran dfather died 5 years ago.His grandfatherfor 5 years.4 His un cle left the city 2 hours ago.His unclthe city2 hours.三现在完成时与一般过去时的区别：(1) 一般过去时表示过去发生的动作或存在的状态；现在完成时表示过去发生的某一动作对 现在