Since 用來說明動作起始時間,而for用來說明動作延續(xù)時間長度.
比如說 ：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.
但是也并非有for 作為時間狀語的句子都用現(xiàn)在完成時.
I worked here for more than twenty years.
(我現(xiàn)在已不在這里工作.)
I have worked here for many years.
(現(xiàn)在我仍在這里工作.)