问题补充:
Mr. Smith, in the factory for thirty years, is on the way back to his village.
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:考查非谓语动词。for+一段时间,常与完成时连用,根据“for thirty years”可知,史密斯先生已经在这家工厂工作了30年,having worked相当于who has worked。故选D。