_____ all that _____ to be done been done?

all that can be done been done. all that can be done has been done Has all that can be done been done? all that can be done has been done. ____all that ____ to be done been done? Everything _____ has been done have been done 和 to be done all that can be done has been done.中的that为 all that can be done has been done 为什么要用has,不用have Has____could be done been done to save the injured.A.all B.w 在all that should be done has been done用了has,但在all that shoul all the things should be done have been done already