现在完成时态的动词转换

延续性动词与非延续性动词（瞬间动词）的区别

在英语中，延续性动词表示能够延续的动作，如，study，work，keep，read，sing，live，teach等。它往往表示经验或经历；非延续性动词也称短暂性动词、终止性动词或瞬间动词，表示不能延续的动作，改动作发生后立即结束，如die, come, leave, close open, begin, leave ,borrow, lend, start, marry等。它往往表示行为的结果。二者的区别如下:

1．延续性动词可以与“时间段”（for+时间段，since+时间点╱从句）连用，而非延续性动词不能与“时间段”连用但可以和“时间点”连用

2．句中有“时间段”或since时应用延续性动词代替非延续性动词。

3.二者均可用句型“It is╱has been +时间段+since+从句（使用一般过去时态）替代。

如果since从句的谓语动词是瞬间性动词，表示肯定意义；如果since从句的谓语动词是延续性动词，则表示否定意义。

1) It is / has been ten years since he left Beijing.

自从他离开北京已经十年了。

分析：since从句中的left是leave的过去式，是瞬间性动词，表示肯定的意思，left译为“离开”

2) It is / has been ten years since he was a doctor.

他不当医生已经十年了。

t is three years since I smoked. 我已经戒烟三年了。

It is three years since I stopped smoking。我已经戒烟三年了It is ten years since we left. 自从我们离开已经有十年了。

4、用于till和until从句的差异

1）延续动词用于肯定句，表示“做……，直到……”

2）瞬间动词用于否定句，表示“到……，才……”

eg. 1.He didn't come back until ten o'clock. 他到10点才回来。

2.He slept until ten o'clock. 他一直睡到10点。

注意：1.非延续性动词可以在现在完成时的否定句中作谓语，并可以与for，since引导的时间状语连用，表示动作的延续过程。

eg. He hasn’t borrowed any books for half a year.

2. 在现在完成时的肯定句中，非延续性动词作谓语时不能与for，since引导的表示一段时间的状语连用，但可以用其他句式来表示同一个意思。例如：

He has been away from Beijing for two years.

= He left Beijing two years ago.

= It is two years since he left Beijing.

= Two years has passed since he left Beijing

三、瞬间动词到延续性动词的转换：

1. 他离开这儿已经六天了。

He has been away from here for 6 days / since 6 days ago.

2. 他父亲死了3年了。

His father has been dead for 3 years / since 3 years ago.

=It’s 3years since his father died.

=His father died 3 years ago.

同学们在使用这两类动词作谓语动词时，常会出现错误。例如：（误）Tom has bought the book for a week.

（正）Tom has had the book for a week.

（误）My father had joined the Party for ten years.

（正）My father has been in the Party for ten years.