答案：D

题目分析：作句子主语，故用动名词形式。expose和其逻辑主语之间是被动关系，故用动名词的被动式，故选D。

点评：动名词的被动式：当动名词的逻辑主语是行为承受者时，用被动语态。如： She is proud of being admitted into the university. 她为被大学录取而感到自豪。The meeting was put off without his having been consulted. 会议延期并未和他商量。