英语的应用越来越广泛了，我们必须好好来学习英语知识。对此精品学习网小学频道编辑为大家整理了小学六年级英语语法讲解：比较since和for。详情如下：

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.

(我现在已不在这里工作。)

I have worked here for many years.

(现在我仍在这里工作。)

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)　(对) Tom has studied Russian for three years.

= Tom began to study Russian three years ago, and is still studying it now.

2)　(错) 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.

希望大家能够认真阅读这篇小学六年级英语语法讲解：比较since和for，以便在英语学习上取得优异的成绩。

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