All that can be done .A. has been doneB. have been doneC. have doneD. has done

问题补充：

All that can be done .

A. has been done

B. have been done

C. have done

D. has done

答案：

(答案→)A. has been done

B. have been done

C. have done

D. has done

解析：All作主语，指的是事情或抽象概念时，常用单数，谓语动词也用单数。