—I regret to tell you that John has been fired.—I can hardly believe my ears. He is such a

问题补充：

—I regret to tell you that John has been fired.

—I can hardly believe my ears. He is such a fine worker.

A. telling

B. having told

C. to tell

D. to have told

答案：

A. telling

B. having told

(答案→)C. to tell

D. to have told

解析：句意：——我很遗憾地告诉你,约翰已经被解雇了。——我几乎不能相信我的耳朵。他是一个好工人。regret to do sth. 很遗憾地/抱歉地做...（事情还没有做）；regret doing sth. 很遗憾/后悔做了...（为已经做过的事而感到...）。根据句意，

故选。