新编实用英语2Unit 7.ppt

现在完成时 (Present Perfect Tense) 四、现在完成时的注意事项 1. 现在完成时的“已完成”用法通常不与瞬间即逝的动词连用， 不能和表示一段时间的状语连用。例如： (1)He has come back for three weeks. (错) (2)He came back three weeks ago. (正确) (3)I have joined the army for ten years. (错) (4)I have been in the army for ten years. (正确) 2. 在由in(for， over， during)the past(last， recent)few(two， three， several)days(weeks， months， years)以及so far， up to the present， up to now， by now等构成的表示时间状语的结构中， 也常用现在完成时表示动作的持续。例如： (1)We have achieved great success in the past few years(over the past ten years). 在过去几年(10年)中我们取得了极大的成功。 (2)Up to now， I have learned three thousand new words. 到现在为止， 我已学会了3000新单词。 (3)Perhaps she has made several friends by now. 到现在， 她很可能已交了几个朋友了。 Grammar 现在完成时 (Present Perfect Tense) 3. have(has)been to与have(has)gone to的用法比较：两者都表示“去某地”， 但have(has)been to的意思是“到过某地(现在此人已返回)”， 侧重经历；而have(has)gone to的意思是“已经去了某地(现在此人已经到了那里或正在途中)”， 侧重此人已不在此地。例如： (1)He has been to Dalian(many times). 他去过大连(好多次)。 (2)He has gone to Dalian. 他已去大连了。 4. 在“This is(It is)the first(second，....)time that...”句型中， that从句要用现在完成时。在“It is(has been)...since...”结构中， 主句经常要用完成时， 也可用一般现在时， 但since引导的从句要用一般过去时。例如： (1)This is the third time that I have visited the Great Wall. 这已是我第三次来长城了。 (2)It has been(is)about 2 years since I came to Nankai University. 自从我来到南开大学已有近两年了。 (3)It has been(is)a long time since I last came to the town. 自从我上次到城里来已有很长时间了。 Grammar 现在完成时 (Present Perfect Tense) 5. 现在完成时中较少使用由where和when引导的疑问句。因为这两种疑问句的询问者关心的是过去所发生的事情的地点或事情发生的具体时间。例如： (1)—When and where did you buy this computer?你是何时何地买的这台计算机? —I bought it last Sunday at the supermarket. 我上个星期天在超市买的。 (2)—Where were you just now?你刚才去哪了? —I looked for you everywhere. 我在到处找你。 但如果强调这一动作对现在造成的影响或结果， 也可用于现在完成时。例如： (3)—Where have you been just now?你刚才去哪了? —We have been looking for you all the time. 我们在到处找你。 —I have been to the library. 我去图书馆了。 Grammar PART I Being All Ears PART II Talking Face to Face PART III Maintaining a Sharp Eye PART IV Trying Your Hand Weather and Environment PART I Sights