选择第2题：No one was surprised at -------the examination.

C.
at后面接动名词作介词宾语,故为passing,当动名词的主语与句子主语不一致时用物主代词one's的形式来做动名词的逻辑主语,故用his.
如果不用动名词形式可以使用从句：
No one was surprised at that he passed the examination.