问题补充：
---- What do you think made Mary so upset ?
---- .
A. As she lost
B. Lost
C. Losing
D. Because of losing
答案：
A. As she lost
B. Lost
(答案→)C. Losing
D. Because of losing
解析：考查动名词做主语，句意是：什么使玛丽这么难过？--她丢了新自行车。说明回答的内容是主语，完整的句子是Losing her new bicycle made mary so upset。选C。
