IamsorrythatIhavekeptyou

来源：语文精选馆 1.44W

I am sorry that I have kept you ________ me so long.

A ing B. to wait C ing for D wait for

C　点拨:keep sb. doing sth.使某人一直做某事。wait 为不及物动词，接名词时需带介词for，故选C。