that I was a regular visitor the servant let me in.A. Having seenB. SeenC. SeeingD. To s

问题补充：

that I was a regular visitor, the servant let me in.

A. Having seen

B. Seen

C. Seeing

D. To see

答案：

A. Having seen

B. Seen

(答案→)C. Seeing

D. To see

解析：考查非谓语动词。主语the servant与see之间是主动关系，所以用现在分词，句意：看到我是一个常客，这位仆人让我进来。所以选C。