比较since和for-英语语法

Since 用来说明动作起始时间，for用来说明动作延续时间长度。
I have lived here for more than twenty years.
I have lived here since I was born..
My aunt has worked in a clinic since 1949.
Some new oilfields have been opened up since 1976.
I have known Xiao Li since she was a little girl.
My brother has been in the Youth League for two years.
I have not heard from my uncle for a long time.

注意：并非有for 作为时间状语的句子都用现在完成时。
I worked here for more than twenty years.

I have worked here for many years.

小窍门：当现在完成时+一段时间，这一结构中，我们用下面的公式转化，很容易就能排除非延续动词在完成时中的误使。
1) Tom has studied Russian for three years.
= Tom began to study Russian three years ago， and is still studying it now.
2) Harry has got married for six years.
= Harry began to get married six years ago， and is still getting married now.
显然，第二句不对，它应改为 Harry got married six years ago.或 Harry has been married for six years.

发布者：ws2012

来源：在职研究生网本页网址：http://zzy.china-b.com/gctwk/yy/20090629/1984847_1.html

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