現(xiàn)在完成時(shí)
1.表示過(guò)去發(fā)生的但對(duì)現(xiàn)在有影響的動(dòng)作,可以不用時(shí)間狀語(yǔ).也可以和一些表示不定過(guò)去的時(shí)間狀語(yǔ)連用,比如already,yet,ever,never,just,once,recently 等.
1).i have been to Peking many times.我多次去過(guò)北京（現(xiàn)在對(duì)北京有所了解）
2).he has bought a car.(現(xiàn)在他有車可以開了)
2.表示從過(guò)去某時(shí)間開始一直延續(xù)到現(xiàn)在的動(dòng)作.一般要跟個(gè)表示一段時(shí)間的狀語(yǔ)since,so far,in recently years,for +時(shí)間段.
例如
1）.he has lived here since 1949.
2) he has lived here for 40 years.
過(guò)去完成時(shí)
表示過(guò)去某一時(shí)刻以前已經(jīng)完成的動(dòng)作,常由by,before等.主要是賓語(yǔ)或定語(yǔ)從句中常見.狀語(yǔ)從句也會(huì)用到
1）by the end of last year,i had worked in this college for ten years.去年年底是過(guò)去時(shí)間,而在大學(xué)工作十年是在去年年底之前,故用過(guò)去完成)
2）he had been a teacher for years before he became a writer.(成為作家是過(guò)去式,而做老師是在成為作家之前,過(guò)去的過(guò)去就用過(guò)去完成式)
3）he knew that he had made a mistaken (他知道為過(guò)去式,而犯錯(cuò)是在知道之前,過(guò)去的過(guò)去)
不知清楚了沒?