at failing in the maths exam, John wouldn't like to talk about it to his parents.
A. Disappointing
B. Having disappointed
C. Disappointed
D. To be disappointed
网友回答
A. Disappointing
B. Having disappointed
(答案→)C. Disappointed
D. To be disappointed
解析：考查非谓语动词。be disappointed at sth/doing sth因某事而感到失望，disappointed是形容词化的过去分词，类似的还有worried, interested, lost, absorbed等，根据句意可知，是发生过的事情，而不定式表将来，排除D，故选C。