—Mr. Johnson, I’m really sorry ________ you waiting for so long a time.
—I know you are very busy at the moment.
A . to have kept B . to keep
C . to be keeping D . to have been kept
A
【详解】
考查非谓语动词。句意: —— 约翰逊先生,我真的很抱歉让你等了这么长时间。 —— 我知道你现在很忙。 be sorry to do sth.“ 抱歉做某事 ” ,此处是动词不定式做原因状语,非谓语动词 keep 的动作明显先于谓语动词,所以用动词不定式的完成式,故选 A 。