Though trying really hard they acknowledged at last.A. defeatedB. defeatingC. having def

问题补充：

Though trying really hard, they acknowledged at last.

A. defeated

B. defeating

C. having defeated

D. having been defeated

答案：

A. defeated

B. defeating

C. having defeated

(答案→)D. having been defeated

解析：考查acknowledge用法。承认做某事acknowledge doing sth. acknowledged having done表示动作已经发生

句意为，尽管很努力地尝试了，他们还是最终成人被打败了。