I’m very sorry to keep you for a long timeA. waitB. waitsC. waitingD. to wait

问题补充：

I’m very sorry to keep you for a long time

A. wait

B. waits

C. waiting

D. to wait

答案：

A. wait

B. waits

(答案→)C. waiting

D. to wait

解析：考查固定用法。keep sb. doing sth.“让某人一直做某事”。句意“让你等这么久真是抱歉。”故选C。