成都新东方酷学酷玩英语为大家讲解英语语法知识：since和for的比较

    英语语法的学习不是一朝一夕，是需要长期积累的，每天积累一个语法知识，长期坚持你会发现语法没有想象的那么难，下面一起来看看成都酷学酷玩英语为大家带来的语法知识吧：
    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. 【纠错】