I must apologize for having you waiting for so long.

I must apologize for having you waiting for so long. I am very sorry for keeping you waiting so long. I\\\'v been waiting for you so long I must apologize for interrupting you.可以改为“I must apologize 初中英语I'm sorry to have you waiting for so long for Marcia,and i waiting for you a long time sorry to keep you waiting for such a long time .I must say s you came me after so long before I have been waiting for you I'm sorry.I have kept you ()for me so long.A:wait B:waiting I‘m sorry to have you waiting so long for Marcia ,and I’m af I'm sorry to have you waiting so long for Marcia ,and I’m af i must apologize for not having let yu know earlier这里为什么用了完成