現(xiàn)在完成時和一般過去時的區(qū)別
1.現(xiàn)在完成時和一般過去時都表示在過去完成的動作,但現(xiàn)在完成時強調(diào)這一動作與現(xiàn)在的關(guān)系,如對現(xiàn)在產(chǎn)生的結(jié)果、影響等,而一般過去時則表示動作發(fā)生在過去,一般不表示和現(xiàn)在的關(guān)系.試比較：
① Who has opened the door?誰把門開了?（現(xiàn)在門還開著）
Who opened the door?誰開的門?(指過去,與現(xiàn)在無關(guān).現(xiàn)在門是關(guān)著還是開著,沒有說明.)
② — Have you had your lunch?你吃過午飯沒有?（意即你現(xiàn)在不餓嗎?）
— Yes,I have.吃了.（意即我現(xiàn)在飽了,不要再吃了.）
— When did you have it?你什么時候吃的?（說話人感興趣的是“吃”這一動作發(fā)生在什么時候.）
2.一般過去時常與具體的時間狀語連用,而現(xiàn)在完成時通常與模糊的時間狀語連用,或無時間狀語.一般過去時的時間狀語：yesterday,once,last week,...ago,in 1980,in October,just now等具體的時間狀語.
現(xiàn)在完成時的時間狀語：for,since,so far,ever,never,just,yet,till/ until,up to now,in past/last years,always等不確定的時間狀語.
共同的時間狀語：
this morning,tonight,this April,now,ever,before,already,recently,lately等.
3.現(xiàn)在完成時表示持續(xù)到現(xiàn)在的動作或狀態(tài),動詞一般是延續(xù)性的,如 live,teach,learn,work,study,know等.
過去時常用的非延續(xù)性動詞有come,go,leave,start,die,finish,become,get married等.eg.
① I saw this film yesterday.（強調(diào)看的動作發(fā)生過了.）
I have seen this film.(強調(diào)對現(xiàn)在的影響,電影的內(nèi)容已經(jīng)知道了.)
② He has been in the League for three years.(在團內(nèi)的狀態(tài)可延續(xù))
He has been a League member for three years.(是團員的狀態(tài)可持續(xù))
He joined the League three years ago.(三年前入團,joined為短暫行為.)
切記：句子中如有一般過去時的時間狀語（如yesterday,last week,in 1960）時,不能使用現(xiàn)在完成時,要用過去時.
(錯) Tom has written a letter to his parents last night.
(對) Tom wrote a letter to his parents last night.
對于表動作和結(jié)果的動詞,我說兩組,你就明白了.
look for ,尋找,強調(diào)尋找的動作.
find 找到,強調(diào)找到的結(jié)果.
I've looked for my pen everywhere ,but I couldn't find it .
listen 聽,強調(diào)聽的動作
hear 聽到,強調(diào)聽的結(jié)果
I listened carefully,but could hear nothing .
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