Walter offered us a lift when he was leaving the office but our work we refused his off

问题补充：

Walter offered us a lift when he was leaving the office, but our work , we refused his offer.

A. not finishing

B. had not been finished

C. not having finished

D. not finished

答案：

A. not finishing

B. had not been finished

C. not having finished

(答案→)D. not finished

解析：在这里，our work处在逗号位置，作整个句子的原因状语，这里应填非谓语动词。work和finish存在逻辑上的被动关系，所以应该用过去分词，故选D。