—did your uncle leave his hometown?—He for nearly twenty years.A. When; has leftB. When;

问题补充：

—did your uncle leave his hometown?

—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：when什么时候；how long多长；根据下文时间状语，将近二十年了。可知上文提问的是时间长短，下文描述的是从过去某时持续到现在的状态，故谓语动词用持续性动词，故选B。