现在完成时for和since的用法

英语自学网

       
                For和since都表示我们说到的时间从过去开始一直持续到现在，但是for与since不能混用。
       
                例如：
                “I have lived in Italy for 13 years.”
                “I have lived in Italy since 2003.”
                当我们用for的时候，表示一个活动持续一段时间，从过去到现在。
                我们用since的时候，表示过去的行为开始一直持续到现在。
                两句话有同样的含义。for的例子中用了“13年”这个时间，但由于 2003年加上13年就是2016年，即今年。两句话的重点都是现在，“我”继续住在意大利，没有去其他国家。
       
                Since 用来说明动作起始时间，for用来说明动作延续时间长度。
       
                给大家举一些例子, 什么时候该用for和since
                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.
       
                但是并非有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。)
       
               
                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.