为什么这里要选择examining,不选择examined?

题目

为什么这里要选择examining,不选择examined?
After _____________ the old man,the doctor suggested that he ___________ a bad cold.
A.examining,should catch B.examined,had caught
C.examining,had caught D.examined,catch
after不是表示过去式吗?

答案

这里考的是非谓语动词啊,整个句子的谓语是suggested."After _____________ the old man",充当的成分是状语,则exam只能做非谓语,而examining代表主动或一般现在时,examined代表被动或一般过去时,整个句子的主语是“th...