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.

C 动名词的复合结构作介词宾语。