.— John,you ----- go out to play until your homework -------

选 B can’t; is finished
homework,是被做完的,所以一定要用被动语态.这里只有 B 里的 is finished 是被动语态.
C has finished 是现在完成时,不行.
如果要用现在完成时,要说：until your homework has been finished.