All the task ahead of time they decided to go on holiday for a week.A. had been finished

问题补充：

All the task ahead of time, they decided to go on holiday for a week.

A. had been finished

B. were finished

C. having been finished

D. been finished

答案：

A. had been finished

B. were finished

(答案→)C. having been finished

D. been finished

解析：考查独立主格结构。句意：由于所有任务都被提前完成了，他们决定去度假一周。现在分词表示正在进行的伴随性动作，和All the task是主谓关系，如果动作发生在主句谓语之前，则要用完成时态的现在分词，任务是被完成的对象，故用被动语态，选C。