11.10 比較過去時(shí)與現(xiàn)在完成時(shí)
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　 1）過去時(shí)表示過去某時(shí)發(fā)生的動(dòng)作或單純敘述過去的事情，強(qiáng)調(diào)動(dòng)作；現(xiàn)在完成時(shí)為過去發(fā)生的，強(qiáng)調(diào)過去的事情對現(xiàn)在的影響，強(qiáng)調(diào)的是影響。
　
　 2）過去時(shí)常與具體的時(shí)間狀語連用，而現(xiàn)在完成時(shí)通常與模糊的時(shí)間狀語連用，或無時(shí)間狀語。

一般過去時(shí)的時(shí)間狀語:
yesterday, last week，…ago, in1980, in October, just now, 具體的時(shí)間狀語

共同的時(shí)間狀語:　
this morning, tonight,this April, now, once，before, already, recently，lately　

現(xiàn)在完成時(shí)的時(shí)間狀語
for, since, so far, ever, never, just, yet,　　　　　　till / until, up to now, in past years, always,
不確定的時(shí)間狀語
　
　 3）現(xiàn)在完成時(shí)可表示持續(xù)到現(xiàn)在的動(dòng)作或狀態(tài)，動(dòng)詞一般是延續(xù)性的，如live, teach, learn, work, study, know.
　 過去時(shí)常用的非持續(xù)性動(dòng)詞有come, go, leave, start, die, finish, become, get married等。
　舉例：
　 I saw this film yesterday.
　　（強(qiáng)調(diào)看的動(dòng)作發(fā)生過了。）
　 I have seen this film.
　　（強(qiáng)調(diào)對現(xiàn)在的影響，電影的內(nèi)容已經(jīng)知道了。）　
　 Why did you get up so early?
　?。◤?qiáng)調(diào)起床的動(dòng)作已發(fā)生過了。）
　 Who hasn't handed in his paper?　
　?。◤?qiáng)調(diào)有卷子，可能為不公平競爭。）
　 She has returned from Paris.　
　　 她已從巴黎回來了。
　 She returned yesterday.
　　 她是昨天回來了。
　 He has been in the League for three years.
　　(在團(tuán)內(nèi)的狀態(tài)可延續(xù))
　 He has been a League member for three years.
　　(是團(tuán)員的狀態(tài)可持續(xù))
　 He joined the League three years ago.　
　　( 三年前入團(tuán)，joined為短暫行為。)
　 I have finished my homework now.　
　
　 ---Will somebody go and get Dr. White?
　 ---He's already been sent for.　
　 句子中如有過去時(shí)的時(shí)間副詞（如 yesterday, last, week, in 1960）時(shí)，不能使用現(xiàn)在完成時(shí)，要用過去時(shí)。
　 （錯(cuò)）Tom has written a letter to his parents last night.
　 （對）Tom wrote a letter to his parents last night.