问题补充:
The old man, abroad for twenty years, is on the way back to his motherland.
A. to work
B. working
C. to have worked
D. having worked
答案:
A. to work
B. working
C. to have worked
(答案→)D. having worked
解析:此题考查非谓语动词形式如何体现时间顺序。不定式表将来、打算;动词ing形式表主动、进行;由于已经工作,所以选D项。