基础语法-现在完成时.doc

现在完成时构成：主语S +have/has+V过去分词+用法：1.表示过去发生的动作对现在造成的影响或结果,常与时间状语already, yet, recently, lately, never, ever, just, by this time, since then, for a long time, in the past three yearsSo far this year we have seen a fall in house prices by between 5 and 10 percent.China has changed a lot in the past decades.Mr. Liu has written a new book recently.I have already lived here for ten years.I have never/ever been to Beijing.I have worked in this factory since I moved here.2. 表过去已经开始，持续到现在的动作或状态，也许还要继续下去。常与for或since引导的时间状语连用，动词必须为延续性动词，如be, live, teach, learn, work, study, know等He has lived in Beijing since 1980(=since he moved here). Ive been a flight attendant for two years now(=since two years ago).since和for区别：since+时间点/一段时间+ago/从句for+时间段My father has been an engineer since 2005.She has been a doctor since two years ago.I have worked here since I moved here.He has been a policeman for about five years.3. have(has) been to表示曾到过某地；have(has) gone to表示已经去某地了（还没回来） They have been to the Great Wall twice.George has gone to London.It cant be Jack. He has gone to Beijing.4. 现在完成时可以用于条件或时间状语从句，代替将来完成时，表示将来某个时刻之前已经完成He will come as soon as he has finished the homework.Dont get off until the bus has stopped.现在完成时和一般过去时：现在完成时表已完成动作对现在造成影响或结果，强调现在情况；而一般过去时只单纯表示过去的动作或状态，不与现在发生联系。He has lived in Beijing since liberation.表现在仍在He lived in Beijing before liberation.现在是否还在不知道5. 终止性动词表示一个短暂的动作，可用于现在完成时，但是不能与表示一段时间的状语连用，不能说：The film has begun for ten minutes.若需表达此意，有三种方法：(1) 把终止性动词变为同义的延续性动词。如The film has been on for ten minutes. 常见终止性动词转延续性的词有： begin/start-be on leave-be away finish-be over come back-be back die-be dead go out-be out get up-be up borrow-keep buy-have join-be in/be a member of catch a cold-have a cold arrive/get to/reach/go/come-be here/there fall (ill, sick, asleep)-be (ill, sick, asleep) He has been here for two days.I have had the pen for a week.(2) 用句型It is/It has been+一段时间+since从句(一般过去时)。如It is/It has been ten minutes since the film began. Its two weeks since he left here.(3) 把since和for引导的时间状语改为表示过去的时间状语，并用一般过去时。如The film began ten minutes ago.He bought this car three months ago.=he has had this car for three months(=