Although very hard he didn’t pass the exam.A. workB. to workC. workingD. worked

问题补充：

Although very hard, he didn’t pass the exam.

A. work

B. to work

C. working

D. worked

答案：

A. work

B. to work

(答案→)C. working

D. worked

解析：考查分词做让步状语。Work 和后面句子主语构成主动关系，所以使用现在分词。Although可以省略的。句意：尽管他工作非常刻苦，但是仍然不能通过考试。