单选题 Having finished lunch, the case was discussed.
A. they discussed the case B. they had discussed the case
C. the case was discussed D. the case had been discussed

【正确答案】 A

【答案解析】[解析] 结构应用。
现在分词短语作状语时，其逻辑主语应与句中主语一致。句中只能是they在discuss，分词逻辑主语是they，句子主语也应是they，所以选项C、D均不对；而前半句用的是现在分词的完成式，表示动作发生在谓语动词表示的动作之前，所以选项A是答案。