All can be done has been done.A. whichB. thatC. /D. what

问题补充：

All can be done has been done.

A. which

B. that

C. /

D. what

答案：

A. which

(答案→)B. that

C. /

D. what

解析：考查定语从句，先行词是all，定语从句中缺少主语，用关系代词，当先行词被最高级或序数词，不定代词修饰时，定语从关系代词用that，不用which，选A。句意是：所有能做的都已经做了。选B。