比較過(guò)去時(shí)與現(xiàn)在完成時(shí)
　　
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(guò)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(guò)了。）
I have seen this film.
（強(qiáng)調(diào)對(duì)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?
（強(qiáng)調(diào)起床的動(dòng)作已發(fā)生過(guò)了。）
Who hasn't handed in his paper?　
（強(qiáng)調(diào)有卷子，可能為不公平競(jìng)爭(zhēng)。）
She has returned from Paris.　
她已從巴黎回來(lái)了。
She returned yesterday.
她是昨天回來(lái)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(guò)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(guò)去時(shí)。
（錯(cuò)）Tom has written a letter to his parents last night.
（對(duì)）Tom wrote a letter to his parents last night.