To his disappointment, the opinion he tried to stick wrong.
A. to prove
B. to proving
C. to was proved
D. to proved
网友回答
A. to prove
B. to proving
C. to was proved
(答案→)D. to proved
解析：句意：使他失望的是，他努力坚持的观点结果是错的。分析句子成分可知：主语是the opinion，后面是定语从句，tried to stick后面缺少to，stick to“坚持”，proved是谓语动词，所以选D。