问题补充:
--- did your uncle leave his home town?.
--- Let me see. He for nearly twenty years.
A. When; has left
B. When; has been away
C. How long; has left
D. How long; has been away
答案:
A. When; has left
(答案→)B. When; has been away
C. How long; has left
D. How long; has been away
解析:句意:你的叔叔什么时候离开了他的家乡?——让我想想。他已经离开将近二十年了。结合语境可知上文描述的是过去发生的动作,故用一般过去时态。下文描述的是从过去一直持续到现在的动作,故用现在完成时态。瞬间动词不能和表示一段时间的时间状语连用,leave表示瞬间动作,故选B。