小升初必備語法：比較過去時與現(xiàn)在完成時

1)過去時表示過去某時發(fā)生的動作或單純敘述過去的事情，強調(diào)動作;現(xiàn)在完成時為過去發(fā)生的，強調(diào)過去的事情對現(xiàn)在的影響，強調(diào)的是影響。

　　2)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, last week，…ago, in1980, in October, just now, 具體的時間狀語

　　共同的時間狀語:

　　this morning, tonight,this April, now, once，before, already, recently，lately

　　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 years, always,

　　不確定的時間狀語

　　3)現(xiàn)在完成時可表示持續(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.

　　過去時常用的非持續(xù)性動詞有come, go, leave, start, die, finish, become, get married等。

　　舉例：

　　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。)

　　Why did you get up so early?

　　(強調(diào)起床的動作已發(fā)生過了。)

　　Who hasn't handed in his paper?

　　(強調(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。)

　　I have finished my homework now.

　　---Will somebody go and get Dr. White?

　　---He's already been sent for.

　　句子中如有過去時的時間副詞(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.