While building a tunnel through the mountain, .A. an underground lake was discoveredB. the

网友回答

A. an underground lake was discovered
B. there was an underground lake discovered
C. a lake was discovered underground
(答案→)D. the workers discovered an underground lake
解析：主要测试一致关系。当分词作状语时，其逻辑主语就是句子主语。又因为现在分词表主动、进行，过去分词表被动、完成，所以只有选项D中的主语the workers才能发出building这个动作。