現(xiàn)在完成時(shí)的定義
  現(xiàn)在完成時(shí)既可表示過(guò)去發(fā)生的動(dòng)作對(duì)現(xiàn)在所造成的結(jié)果或影響(此時(shí)通常連用的時(shí)間狀語(yǔ)有already, yet, just, ever, before),也可表示動(dòng)作從過(guò)去某時(shí)間開(kāi)始,一直持續(xù)到現(xiàn)在,并且還有可能持續(xù)下去(此時(shí)通常連用的時(shí)間狀語(yǔ)有this month / week / year, these days, recently / lately, in the past few + 時(shí)間段, since +時(shí)間點(diǎn), for + 時(shí)間段)。如:
  I have just finished my work. 我把工作做完。
  Have you ever been to Beijing? 你曾經(jīng)去過(guò)北京嗎?
  I have lived for ten years. 我在這兒住了十年了。
  We have studied here since 2003. 我們自2003年來(lái)就在這兒讀書(shū)了。
  2. 現(xiàn)在完成時(shí)的結(jié)構(gòu)
  現(xiàn)在完成時(shí)由“have / has + 過(guò)去分詞”構(gòu)成。