I am sorry to have you so long.A. waitedB. to waitC. waitingD. to be waiting

问题补充：

I am sorry to have you so long.

A. waited

B. to wait

C. waiting

D. to be waiting

答案：

A. waited

B. to wait

(答案→)C. waiting

D. to be waiting

解析：考查非谓语动词。have sb. doing sth让某人一直做某事，句意：对不起让你一直等这么久。故选C。